1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation. Oracle designates this
7 * particular file as subject to the "Classpath" exception as provided
8 * by Oracle in the LICENSE file that accompanied this code.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 */
24
25 /* pngrtran.c - transforms the data in a row for PNG readers
26 *
27 * Copyright (c) 2018-2019 Cosmin Truta
28 * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
29 * Copyright (c) 1996-1997 Andreas Dilger
30 * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
31 *
32 * This code is released under the libpng license.
33 * For conditions of distribution and use, see the disclaimer
34 * and license in png.h
35 *
36 * This file contains functions optionally called by an application
37 * in order to tell libpng how to handle data when reading a PNG.
38 * Transformations that are used in both reading and writing are
39 * in pngtrans.c.
40 */
41
42 #include "pngpriv.h"
43
44 #ifdef PNG_ARM_NEON_IMPLEMENTATION
45 # if PNG_ARM_NEON_IMPLEMENTATION == 1
46 # define PNG_ARM_NEON_INTRINSICS_AVAILABLE
47 # if defined(_MSC_VER) && defined(_M_ARM64)
48 # include <arm64_neon.h>
49 # else
50 # include <arm_neon.h>
51 # endif
52 # endif
53 #endif
54
55 #ifdef PNG_READ_SUPPORTED
56
57 /* Set the action on getting a CRC error for an ancillary or critical chunk. */
58 void PNGAPI
59 png_set_crc_action(png_structrp png_ptr, int crit_action, int ancil_action)
60 {
61 png_debug(1, "in png_set_crc_action");
62
63 if (png_ptr == NULL)
64 return;
65
66 /* Tell libpng how we react to CRC errors in critical chunks */
67 switch (crit_action)
68 {
69 case PNG_CRC_NO_CHANGE: /* Leave setting as is */
70 break;
71
72 case PNG_CRC_WARN_USE: /* Warn/use data */
73 png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
74 png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE;
75 break;
76
77 case PNG_CRC_QUIET_USE: /* Quiet/use data */
78 png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
79 png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE |
80 PNG_FLAG_CRC_CRITICAL_IGNORE;
81 break;
82
83 case PNG_CRC_WARN_DISCARD: /* Not a valid action for critical data */
84 png_warning(png_ptr,
85 "Can't discard critical data on CRC error");
86 /* FALLTHROUGH */
87 case PNG_CRC_ERROR_QUIT: /* Error/quit */
88
89 case PNG_CRC_DEFAULT:
90 default:
91 png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
92 break;
93 }
94
95 /* Tell libpng how we react to CRC errors in ancillary chunks */
96 switch (ancil_action)
97 {
98 case PNG_CRC_NO_CHANGE: /* Leave setting as is */
99 break;
100
101 case PNG_CRC_WARN_USE: /* Warn/use data */
102 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
103 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE;
104 break;
105
106 case PNG_CRC_QUIET_USE: /* Quiet/use data */
107 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
108 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE |
109 PNG_FLAG_CRC_ANCILLARY_NOWARN;
110 break;
111
112 case PNG_CRC_ERROR_QUIT: /* Error/quit */
113 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
114 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_NOWARN;
115 break;
116
117 case PNG_CRC_WARN_DISCARD: /* Warn/discard data */
118
119 case PNG_CRC_DEFAULT:
120 default:
121 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
122 break;
123 }
124 }
125
126 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
127 /* Is it OK to set a transformation now? Only if png_start_read_image or
128 * png_read_update_info have not been called. It is not necessary for the IHDR
129 * to have been read in all cases; the need_IHDR parameter allows for this
130 * check too.
131 */
132 static int
133 png_rtran_ok(png_structrp png_ptr, int need_IHDR)
134 {
135 if (png_ptr != NULL)
136 {
137 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) != 0)
138 png_app_error(png_ptr,
139 "invalid after png_start_read_image or png_read_update_info");
140
141 else if (need_IHDR && (png_ptr->mode & PNG_HAVE_IHDR) == 0)
142 png_app_error(png_ptr, "invalid before the PNG header has been read");
143
144 else
145 {
146 /* Turn on failure to initialize correctly for all transforms. */
147 png_ptr->flags |= PNG_FLAG_DETECT_UNINITIALIZED;
148
149 return 1; /* Ok */
150 }
151 }
152
153 return 0; /* no png_error possible! */
154 }
155 #endif
156
157 #ifdef PNG_READ_BACKGROUND_SUPPORTED
158 /* Handle alpha and tRNS via a background color */
159 void PNGFAPI
160 png_set_background_fixed(png_structrp png_ptr,
161 png_const_color_16p background_color, int background_gamma_code,
162 int need_expand, png_fixed_point background_gamma)
163 {
164 png_debug(1, "in png_set_background_fixed");
165
166 if (png_rtran_ok(png_ptr, 0) == 0 || background_color == NULL)
167 return;
168
169 if (background_gamma_code == PNG_BACKGROUND_GAMMA_UNKNOWN)
170 {
171 png_warning(png_ptr, "Application must supply a known background gamma");
172 return;
173 }
174
175 png_ptr->transformations |= PNG_COMPOSE | PNG_STRIP_ALPHA;
176 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
177 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
178
179 png_ptr->background = *background_color;
180 png_ptr->background_gamma = background_gamma;
181 png_ptr->background_gamma_type = (png_byte)(background_gamma_code);
182 if (need_expand != 0)
183 png_ptr->transformations |= PNG_BACKGROUND_EXPAND;
184 else
185 png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND;
186 }
187
188 # ifdef PNG_FLOATING_POINT_SUPPORTED
189 void PNGAPI
190 png_set_background(png_structrp png_ptr,
191 png_const_color_16p background_color, int background_gamma_code,
192 int need_expand, double background_gamma)
193 {
194 png_set_background_fixed(png_ptr, background_color, background_gamma_code,
195 need_expand, png_fixed(png_ptr, background_gamma, "png_set_background"));
196 }
197 # endif /* FLOATING_POINT */
198 #endif /* READ_BACKGROUND */
199
200 /* Scale 16-bit depth files to 8-bit depth. If both of these are set then the
201 * one that pngrtran does first (scale) happens. This is necessary to allow the
202 * TRANSFORM and API behavior to be somewhat consistent, and it's simpler.
203 */
204 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
205 void PNGAPI
206 png_set_scale_16(png_structrp png_ptr)
207 {
208 png_debug(1, "in png_set_scale_16");
209
210 if (png_rtran_ok(png_ptr, 0) == 0)
211 return;
212
213 png_ptr->transformations |= PNG_SCALE_16_TO_8;
214 }
215 #endif
216
217 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
218 /* Chop 16-bit depth files to 8-bit depth */
219 void PNGAPI
220 png_set_strip_16(png_structrp png_ptr)
221 {
222 png_debug(1, "in png_set_strip_16");
223
224 if (png_rtran_ok(png_ptr, 0) == 0)
225 return;
226
227 png_ptr->transformations |= PNG_16_TO_8;
228 }
229 #endif
230
231 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
232 void PNGAPI
233 png_set_strip_alpha(png_structrp png_ptr)
234 {
235 png_debug(1, "in png_set_strip_alpha");
236
237 if (png_rtran_ok(png_ptr, 0) == 0)
238 return;
239
240 png_ptr->transformations |= PNG_STRIP_ALPHA;
241 }
242 #endif
243
244 #if defined(PNG_READ_ALPHA_MODE_SUPPORTED) || defined(PNG_READ_GAMMA_SUPPORTED)
245 static png_fixed_point
246 translate_gamma_flags(png_structrp png_ptr, png_fixed_point output_gamma,
247 int is_screen)
248 {
249 /* Check for flag values. The main reason for having the old Mac value as a
250 * flag is that it is pretty near impossible to work out what the correct
251 * value is from Apple documentation - a working Mac system is needed to
252 * discover the value!
253 */
254 if (output_gamma == PNG_DEFAULT_sRGB ||
255 output_gamma == PNG_FP_1 / PNG_DEFAULT_sRGB)
256 {
257 /* If there is no sRGB support this just sets the gamma to the standard
258 * sRGB value. (This is a side effect of using this function!)
259 */
260 # ifdef PNG_READ_sRGB_SUPPORTED
261 png_ptr->flags |= PNG_FLAG_ASSUME_sRGB;
262 # else
263 PNG_UNUSED(png_ptr)
264 # endif
265 if (is_screen != 0)
266 output_gamma = PNG_GAMMA_sRGB;
267 else
268 output_gamma = PNG_GAMMA_sRGB_INVERSE;
269 }
270
271 else if (output_gamma == PNG_GAMMA_MAC_18 ||
272 output_gamma == PNG_FP_1 / PNG_GAMMA_MAC_18)
273 {
274 if (is_screen != 0)
275 output_gamma = PNG_GAMMA_MAC_OLD;
276 else
277 output_gamma = PNG_GAMMA_MAC_INVERSE;
278 }
279
280 return output_gamma;
281 }
282
283 # ifdef PNG_FLOATING_POINT_SUPPORTED
284 static png_fixed_point
285 convert_gamma_value(png_structrp png_ptr, double output_gamma)
286 {
287 /* The following silently ignores cases where fixed point (times 100,000)
288 * gamma values are passed to the floating point API. This is safe and it
289 * means the fixed point constants work just fine with the floating point
290 * API. The alternative would just lead to undetected errors and spurious
291 * bug reports. Negative values fail inside the _fixed API unless they
292 * correspond to the flag values.
293 */
294 if (output_gamma > 0 && output_gamma < 128)
295 output_gamma *= PNG_FP_1;
296
297 /* This preserves -1 and -2 exactly: */
298 output_gamma = floor(output_gamma + .5);
299
300 if (output_gamma > PNG_FP_MAX || output_gamma < PNG_FP_MIN)
301 png_fixed_error(png_ptr, "gamma value");
302
303 return (png_fixed_point)output_gamma;
304 }
305 # endif
306 #endif /* READ_ALPHA_MODE || READ_GAMMA */
307
308 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
309 void PNGFAPI
310 png_set_alpha_mode_fixed(png_structrp png_ptr, int mode,
311 png_fixed_point output_gamma)
312 {
313 int compose = 0;
314 png_fixed_point file_gamma;
315
316 png_debug(1, "in png_set_alpha_mode");
317
318 if (png_rtran_ok(png_ptr, 0) == 0)
319 return;
320
321 output_gamma = translate_gamma_flags(png_ptr, output_gamma, 1/*screen*/);
322
323 /* Validate the value to ensure it is in a reasonable range. The value
324 * is expected to be 1 or greater, but this range test allows for some
325 * viewing correction values. The intent is to weed out users of this API
326 * who use the inverse of the gamma value accidentally! Since some of these
327 * values are reasonable this may have to be changed:
328 *
329 * 1.6.x: changed from 0.07..3 to 0.01..100 (to accommodate the optimal 16-bit
330 * gamma of 36, and its reciprocal.)
331 */
332 if (output_gamma < 1000 || output_gamma > 10000000)
333 png_error(png_ptr, "output gamma out of expected range");
334
335 /* The default file gamma is the inverse of the output gamma; the output
336 * gamma may be changed below so get the file value first:
337 */
338 file_gamma = png_reciprocal(output_gamma);
339
340 /* There are really 8 possibilities here, composed of any combination
341 * of:
342 *
343 * premultiply the color channels
344 * do not encode non-opaque pixels
345 * encode the alpha as well as the color channels
346 *
347 * The differences disappear if the input/output ('screen') gamma is 1.0,
348 * because then the encoding is a no-op and there is only the choice of
349 * premultiplying the color channels or not.
350 *
351 * png_set_alpha_mode and png_set_background interact because both use
352 * png_compose to do the work. Calling both is only useful when
353 * png_set_alpha_mode is used to set the default mode - PNG_ALPHA_PNG - along
354 * with a default gamma value. Otherwise PNG_COMPOSE must not be set.
355 */
356 switch (mode)
357 {
358 case PNG_ALPHA_PNG: /* default: png standard */
359 /* No compose, but it may be set by png_set_background! */
360 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
361 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
362 break;
363
364 case PNG_ALPHA_ASSOCIATED: /* color channels premultiplied */
365 compose = 1;
366 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
367 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
368 /* The output is linear: */
369 output_gamma = PNG_FP_1;
370 break;
371
372 case PNG_ALPHA_OPTIMIZED: /* associated, non-opaque pixels linear */
373 compose = 1;
374 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
375 png_ptr->flags |= PNG_FLAG_OPTIMIZE_ALPHA;
376 /* output_gamma records the encoding of opaque pixels! */
377 break;
378
379 case PNG_ALPHA_BROKEN: /* associated, non-linear, alpha encoded */
380 compose = 1;
381 png_ptr->transformations |= PNG_ENCODE_ALPHA;
382 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
383 break;
384
385 default:
386 png_error(png_ptr, "invalid alpha mode");
387 }
388
389 /* Only set the default gamma if the file gamma has not been set (this has
390 * the side effect that the gamma in a second call to png_set_alpha_mode will
391 * be ignored.)
392 */
393 if (png_ptr->colorspace.gamma == 0)
394 {
395 png_ptr->colorspace.gamma = file_gamma;
396 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
397 }
398
399 /* But always set the output gamma: */
400 png_ptr->screen_gamma = output_gamma;
401
402 /* Finally, if pre-multiplying, set the background fields to achieve the
403 * desired result.
404 */
405 if (compose != 0)
406 {
407 /* And obtain alpha pre-multiplication by composing on black: */
408 memset(&png_ptr->background, 0, (sizeof png_ptr->background));
409 png_ptr->background_gamma = png_ptr->colorspace.gamma; /* just in case */
410 png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_FILE;
411 png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND;
412
413 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
414 png_error(png_ptr,
415 "conflicting calls to set alpha mode and background");
416
417 png_ptr->transformations |= PNG_COMPOSE;
418 }
419 }
420
421 # ifdef PNG_FLOATING_POINT_SUPPORTED
422 void PNGAPI
423 png_set_alpha_mode(png_structrp png_ptr, int mode, double output_gamma)
424 {
425 png_set_alpha_mode_fixed(png_ptr, mode, convert_gamma_value(png_ptr,
426 output_gamma));
427 }
428 # endif
429 #endif
430
431 #ifdef PNG_READ_QUANTIZE_SUPPORTED
432 /* Dither file to 8-bit. Supply a palette, the current number
433 * of elements in the palette, the maximum number of elements
434 * allowed, and a histogram if possible. If the current number
435 * of colors is greater than the maximum number, the palette will be
436 * modified to fit in the maximum number. "full_quantize" indicates
437 * whether we need a quantizing cube set up for RGB images, or if we
438 * simply are reducing the number of colors in a paletted image.
439 */
440
441 typedef struct png_dsort_struct
442 {
443 struct png_dsort_struct * next;
444 png_byte left;
445 png_byte right;
446 } png_dsort;
447 typedef png_dsort * png_dsortp;
448 typedef png_dsort * * png_dsortpp;
449
450 void PNGAPI
451 png_set_quantize(png_structrp png_ptr, png_colorp palette,
452 int num_palette, int maximum_colors, png_const_uint_16p histogram,
453 int full_quantize)
454 {
455 png_debug(1, "in png_set_quantize");
456
457 if (png_rtran_ok(png_ptr, 0) == 0)
458 return;
459
460 png_ptr->transformations |= PNG_QUANTIZE;
461
462 if (full_quantize == 0)
463 {
464 int i;
465
466 png_ptr->quantize_index = (png_bytep)png_malloc(png_ptr,
467 (png_alloc_size_t)((png_uint_32)num_palette * (sizeof (png_byte))));
468 for (i = 0; i < num_palette; i++)
469 png_ptr->quantize_index[i] = (png_byte)i;
470 }
471
472 if (num_palette > maximum_colors)
473 {
474 if (histogram != NULL)
475 {
476 /* This is easy enough, just throw out the least used colors.
477 * Perhaps not the best solution, but good enough.
478 */
479
480 int i;
481
482 /* Initialize an array to sort colors */
483 png_ptr->quantize_sort = (png_bytep)png_malloc(png_ptr,
484 (png_alloc_size_t)((png_uint_32)num_palette * (sizeof (png_byte))));
485
486 /* Initialize the quantize_sort array */
487 for (i = 0; i < num_palette; i++)
488 png_ptr->quantize_sort[i] = (png_byte)i;
489
490 /* Find the least used palette entries by starting a
491 * bubble sort, and running it until we have sorted
492 * out enough colors. Note that we don't care about
493 * sorting all the colors, just finding which are
494 * least used.
495 */
496
497 for (i = num_palette - 1; i >= maximum_colors; i--)
498 {
499 int done; /* To stop early if the list is pre-sorted */
500 int j;
501
502 done = 1;
503 for (j = 0; j < i; j++)
504 {
505 if (histogram[png_ptr->quantize_sort[j]]
506 < histogram[png_ptr->quantize_sort[j + 1]])
507 {
508 png_byte t;
509
510 t = png_ptr->quantize_sort[j];
511 png_ptr->quantize_sort[j] = png_ptr->quantize_sort[j + 1];
512 png_ptr->quantize_sort[j + 1] = t;
513 done = 0;
514 }
515 }
516
517 if (done != 0)
518 break;
519 }
520
521 /* Swap the palette around, and set up a table, if necessary */
522 if (full_quantize != 0)
523 {
524 int j = num_palette;
525
526 /* Put all the useful colors within the max, but don't
527 * move the others.
528 */
529 for (i = 0; i < maximum_colors; i++)
530 {
531 if ((int)png_ptr->quantize_sort[i] >= maximum_colors)
532 {
533 do
534 j--;
535 while ((int)png_ptr->quantize_sort[j] >= maximum_colors);
536
537 palette[i] = palette[j];
538 }
539 }
540 }
541 else
542 {
543 int j = num_palette;
544
545 /* Move all the used colors inside the max limit, and
546 * develop a translation table.
547 */
548 for (i = 0; i < maximum_colors; i++)
549 {
550 /* Only move the colors we need to */
551 if ((int)png_ptr->quantize_sort[i] >= maximum_colors)
552 {
553 png_color tmp_color;
554
555 do
556 j--;
557 while ((int)png_ptr->quantize_sort[j] >= maximum_colors);
558
559 tmp_color = palette[j];
560 palette[j] = palette[i];
561 palette[i] = tmp_color;
562 /* Indicate where the color went */
563 png_ptr->quantize_index[j] = (png_byte)i;
564 png_ptr->quantize_index[i] = (png_byte)j;
565 }
566 }
567
568 /* Find closest color for those colors we are not using */
569 for (i = 0; i < num_palette; i++)
570 {
571 if ((int)png_ptr->quantize_index[i] >= maximum_colors)
572 {
573 int min_d, k, min_k, d_index;
574
575 /* Find the closest color to one we threw out */
576 d_index = png_ptr->quantize_index[i];
577 min_d = PNG_COLOR_DIST(palette[d_index], palette[0]);
578 for (k = 1, min_k = 0; k < maximum_colors; k++)
579 {
580 int d;
581
582 d = PNG_COLOR_DIST(palette[d_index], palette[k]);
583
584 if (d < min_d)
585 {
586 min_d = d;
587 min_k = k;
588 }
589 }
590 /* Point to closest color */
591 png_ptr->quantize_index[i] = (png_byte)min_k;
592 }
593 }
594 }
595 png_free(png_ptr, png_ptr->quantize_sort);
596 png_ptr->quantize_sort = NULL;
597 }
598 else
599 {
600 /* This is much harder to do simply (and quickly). Perhaps
601 * we need to go through a median cut routine, but those
602 * don't always behave themselves with only a few colors
603 * as input. So we will just find the closest two colors,
604 * and throw out one of them (chosen somewhat randomly).
605 * [We don't understand this at all, so if someone wants to
606 * work on improving it, be our guest - AED, GRP]
607 */
608 int i;
609 int max_d;
610 int num_new_palette;
611 png_dsortp t;
612 png_dsortpp hash;
613
614 t = NULL;
615
616 /* Initialize palette index arrays */
617 png_ptr->index_to_palette = (png_bytep)png_malloc(png_ptr,
618 (png_alloc_size_t)((png_uint_32)num_palette *
619 (sizeof (png_byte))));
620 png_ptr->palette_to_index = (png_bytep)png_malloc(png_ptr,
621 (png_alloc_size_t)((png_uint_32)num_palette *
622 (sizeof (png_byte))));
623
624 /* Initialize the sort array */
625 for (i = 0; i < num_palette; i++)
626 {
627 png_ptr->index_to_palette[i] = (png_byte)i;
628 png_ptr->palette_to_index[i] = (png_byte)i;
629 }
630
631 hash = (png_dsortpp)png_calloc(png_ptr, (png_alloc_size_t)(769 *
632 (sizeof (png_dsortp))));
633
634 num_new_palette = num_palette;
635
636 /* Initial wild guess at how far apart the farthest pixel
637 * pair we will be eliminating will be. Larger
638 * numbers mean more areas will be allocated, Smaller
639 * numbers run the risk of not saving enough data, and
640 * having to do this all over again.
641 *
642 * I have not done extensive checking on this number.
643 */
644 max_d = 96;
645
646 while (num_new_palette > maximum_colors)
647 {
648 for (i = 0; i < num_new_palette - 1; i++)
649 {
650 int j;
651
652 for (j = i + 1; j < num_new_palette; j++)
653 {
654 int d;
655
656 d = PNG_COLOR_DIST(palette[i], palette[j]);
657
658 if (d <= max_d)
659 {
660
661 t = (png_dsortp)png_malloc_warn(png_ptr,
662 (png_alloc_size_t)(sizeof (png_dsort)));
663
664 if (t == NULL)
665 break;
666
667 t->next = hash[d];
668 t->left = (png_byte)i;
669 t->right = (png_byte)j;
670 hash[d] = t;
671 }
672 }
673 if (t == NULL)
674 break;
675 }
676
677 if (t != NULL)
678 for (i = 0; i <= max_d; i++)
679 {
680 if (hash[i] != NULL)
681 {
682 png_dsortp p;
683
684 for (p = hash[i]; p; p = p->next)
685 {
686 if ((int)png_ptr->index_to_palette[p->left]
687 < num_new_palette &&
688 (int)png_ptr->index_to_palette[p->right]
689 < num_new_palette)
690 {
691 int j, next_j;
692
693 if (num_new_palette & 0x01)
694 {
695 j = p->left;
696 next_j = p->right;
697 }
698 else
699 {
700 j = p->right;
701 next_j = p->left;
702 }
703
704 num_new_palette--;
705 palette[png_ptr->index_to_palette[j]]
706 = palette[num_new_palette];
707 if (full_quantize == 0)
708 {
709 int k;
710
711 for (k = 0; k < num_palette; k++)
712 {
713 if (png_ptr->quantize_index[k] ==
714 png_ptr->index_to_palette[j])
715 png_ptr->quantize_index[k] =
716 png_ptr->index_to_palette[next_j];
717
718 if ((int)png_ptr->quantize_index[k] ==
719 num_new_palette)
720 png_ptr->quantize_index[k] =
721 png_ptr->index_to_palette[j];
722 }
723 }
724
725 png_ptr->index_to_palette[png_ptr->palette_to_index
726 [num_new_palette]] = png_ptr->index_to_palette[j];
727
728 png_ptr->palette_to_index[png_ptr->index_to_palette[j]]
729 = png_ptr->palette_to_index[num_new_palette];
730
731 png_ptr->index_to_palette[j] =
732 (png_byte)num_new_palette;
733
734 png_ptr->palette_to_index[num_new_palette] =
735 (png_byte)j;
736 }
737 if (num_new_palette <= maximum_colors)
738 break;
739 }
740 if (num_new_palette <= maximum_colors)
741 break;
742 }
743 }
744
745 for (i = 0; i < 769; i++)
746 {
747 if (hash[i] != NULL)
748 {
749 png_dsortp p = hash[i];
750 while (p)
751 {
752 t = p->next;
753 png_free(png_ptr, p);
754 p = t;
755 }
756 }
757 hash[i] = 0;
758 }
759 max_d += 96;
760 }
761 png_free(png_ptr, hash);
762 png_free(png_ptr, png_ptr->palette_to_index);
763 png_free(png_ptr, png_ptr->index_to_palette);
764 png_ptr->palette_to_index = NULL;
765 png_ptr->index_to_palette = NULL;
766 }
767 num_palette = maximum_colors;
768 }
769 if (png_ptr->palette == NULL)
770 {
771 png_ptr->palette = palette;
772 }
773 png_ptr->num_palette = (png_uint_16)num_palette;
774
775 if (full_quantize != 0)
776 {
777 int i;
778 png_bytep distance;
779 int total_bits = PNG_QUANTIZE_RED_BITS + PNG_QUANTIZE_GREEN_BITS +
780 PNG_QUANTIZE_BLUE_BITS;
781 int num_red = (1 << PNG_QUANTIZE_RED_BITS);
782 int num_green = (1 << PNG_QUANTIZE_GREEN_BITS);
783 int num_blue = (1 << PNG_QUANTIZE_BLUE_BITS);
784 size_t num_entries = ((size_t)1 << total_bits);
785
786 png_ptr->palette_lookup = (png_bytep)png_calloc(png_ptr,
787 (png_alloc_size_t)(num_entries * (sizeof (png_byte))));
788
789 distance = (png_bytep)png_malloc(png_ptr, (png_alloc_size_t)(num_entries *
790 (sizeof (png_byte))));
791
792 memset(distance, 0xff, num_entries * (sizeof (png_byte)));
793
794 for (i = 0; i < num_palette; i++)
795 {
796 int ir, ig, ib;
797 int r = (palette[i].red >> (8 - PNG_QUANTIZE_RED_BITS));
798 int g = (palette[i].green >> (8 - PNG_QUANTIZE_GREEN_BITS));
799 int b = (palette[i].blue >> (8 - PNG_QUANTIZE_BLUE_BITS));
800
801 for (ir = 0; ir < num_red; ir++)
802 {
803 /* int dr = abs(ir - r); */
804 int dr = ((ir > r) ? ir - r : r - ir);
805 int index_r = (ir << (PNG_QUANTIZE_BLUE_BITS +
806 PNG_QUANTIZE_GREEN_BITS));
807
808 for (ig = 0; ig < num_green; ig++)
809 {
810 /* int dg = abs(ig - g); */
811 int dg = ((ig > g) ? ig - g : g - ig);
812 int dt = dr + dg;
813 int dm = ((dr > dg) ? dr : dg);
814 int index_g = index_r | (ig << PNG_QUANTIZE_BLUE_BITS);
815
816 for (ib = 0; ib < num_blue; ib++)
817 {
818 int d_index = index_g | ib;
819 /* int db = abs(ib - b); */
820 int db = ((ib > b) ? ib - b : b - ib);
821 int dmax = ((dm > db) ? dm : db);
822 int d = dmax + dt + db;
823
824 if (d < (int)distance[d_index])
825 {
826 distance[d_index] = (png_byte)d;
827 png_ptr->palette_lookup[d_index] = (png_byte)i;
828 }
829 }
830 }
831 }
832 }
833
834 png_free(png_ptr, distance);
835 }
836 }
837 #endif /* READ_QUANTIZE */
838
839 #ifdef PNG_READ_GAMMA_SUPPORTED
840 void PNGFAPI
841 png_set_gamma_fixed(png_structrp png_ptr, png_fixed_point scrn_gamma,
842 png_fixed_point file_gamma)
843 {
844 png_debug(1, "in png_set_gamma_fixed");
845
846 if (png_rtran_ok(png_ptr, 0) == 0)
847 return;
848
849 /* New in libpng-1.5.4 - reserve particular negative values as flags. */
850 scrn_gamma = translate_gamma_flags(png_ptr, scrn_gamma, 1/*screen*/);
851 file_gamma = translate_gamma_flags(png_ptr, file_gamma, 0/*file*/);
852
853 /* Checking the gamma values for being >0 was added in 1.5.4 along with the
854 * premultiplied alpha support; this actually hides an undocumented feature
855 * of the previous implementation which allowed gamma processing to be
856 * disabled in background handling. There is no evidence (so far) that this
857 * was being used; however, png_set_background itself accepted and must still
858 * accept '0' for the gamma value it takes, because it isn't always used.
859 *
860 * Since this is an API change (albeit a very minor one that removes an
861 * undocumented API feature) the following checks were only enabled in
862 * libpng-1.6.0.
863 */
864 if (file_gamma <= 0)
865 png_error(png_ptr, "invalid file gamma in png_set_gamma");
866
867 if (scrn_gamma <= 0)
868 png_error(png_ptr, "invalid screen gamma in png_set_gamma");
869
870 /* Set the gamma values unconditionally - this overrides the value in the PNG
871 * file if a gAMA chunk was present. png_set_alpha_mode provides a
872 * different, easier, way to default the file gamma.
873 */
874 png_ptr->colorspace.gamma = file_gamma;
875 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
876 png_ptr->screen_gamma = scrn_gamma;
877 }
878
879 # ifdef PNG_FLOATING_POINT_SUPPORTED
880 void PNGAPI
881 png_set_gamma(png_structrp png_ptr, double scrn_gamma, double file_gamma)
882 {
883 png_set_gamma_fixed(png_ptr, convert_gamma_value(png_ptr, scrn_gamma),
884 convert_gamma_value(png_ptr, file_gamma));
885 }
886 # endif /* FLOATING_POINT */
887 #endif /* READ_GAMMA */
888
889 #ifdef PNG_READ_EXPAND_SUPPORTED
890 /* Expand paletted images to RGB, expand grayscale images of
891 * less than 8-bit depth to 8-bit depth, and expand tRNS chunks
892 * to alpha channels.
893 */
894 void PNGAPI
895 png_set_expand(png_structrp png_ptr)
896 {
897 png_debug(1, "in png_set_expand");
898
899 if (png_rtran_ok(png_ptr, 0) == 0)
900 return;
901
902 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
903 }
904
905 /* GRR 19990627: the following three functions currently are identical
906 * to png_set_expand(). However, it is entirely reasonable that someone
907 * might wish to expand an indexed image to RGB but *not* expand a single,
908 * fully transparent palette entry to a full alpha channel--perhaps instead
909 * convert tRNS to the grayscale/RGB format (16-bit RGB value), or replace
910 * the transparent color with a particular RGB value, or drop tRNS entirely.
911 * IOW, a future version of the library may make the transformations flag
912 * a bit more fine-grained, with separate bits for each of these three
913 * functions.
914 *
915 * More to the point, these functions make it obvious what libpng will be
916 * doing, whereas "expand" can (and does) mean any number of things.
917 *
918 * GRP 20060307: In libpng-1.2.9, png_set_gray_1_2_4_to_8() was modified
919 * to expand only the sample depth but not to expand the tRNS to alpha
920 * and its name was changed to png_set_expand_gray_1_2_4_to_8().
921 */
922
923 /* Expand paletted images to RGB. */
924 void PNGAPI
925 png_set_palette_to_rgb(png_structrp png_ptr)
926 {
927 png_debug(1, "in png_set_palette_to_rgb");
928
929 if (png_rtran_ok(png_ptr, 0) == 0)
930 return;
931
932 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
933 }
934
935 /* Expand grayscale images of less than 8-bit depth to 8 bits. */
936 void PNGAPI
937 png_set_expand_gray_1_2_4_to_8(png_structrp png_ptr)
938 {
939 png_debug(1, "in png_set_expand_gray_1_2_4_to_8");
940
941 if (png_rtran_ok(png_ptr, 0) == 0)
942 return;
943
944 png_ptr->transformations |= PNG_EXPAND;
945 }
946
947 /* Expand tRNS chunks to alpha channels. */
948 void PNGAPI
949 png_set_tRNS_to_alpha(png_structrp png_ptr)
950 {
951 png_debug(1, "in png_set_tRNS_to_alpha");
952
953 if (png_rtran_ok(png_ptr, 0) == 0)
954 return;
955
956 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
957 }
958 #endif /* READ_EXPAND */
959
960 #ifdef PNG_READ_EXPAND_16_SUPPORTED
961 /* Expand to 16-bit channels, expand the tRNS chunk too (because otherwise
962 * it may not work correctly.)
963 */
964 void PNGAPI
965 png_set_expand_16(png_structrp png_ptr)
966 {
967 png_debug(1, "in png_set_expand_16");
968
969 if (png_rtran_ok(png_ptr, 0) == 0)
970 return;
971
972 png_ptr->transformations |= (PNG_EXPAND_16 | PNG_EXPAND | PNG_EXPAND_tRNS);
973 }
974 #endif
975
976 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
977 void PNGAPI
978 png_set_gray_to_rgb(png_structrp png_ptr)
979 {
980 png_debug(1, "in png_set_gray_to_rgb");
981
982 if (png_rtran_ok(png_ptr, 0) == 0)
983 return;
984
985 /* Because rgb must be 8 bits or more: */
986 png_set_expand_gray_1_2_4_to_8(png_ptr);
987 png_ptr->transformations |= PNG_GRAY_TO_RGB;
988 }
989 #endif
990
991 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
992 void PNGFAPI
993 png_set_rgb_to_gray_fixed(png_structrp png_ptr, int error_action,
994 png_fixed_point red, png_fixed_point green)
995 {
996 png_debug(1, "in png_set_rgb_to_gray");
997
998 /* Need the IHDR here because of the check on color_type below. */
999 /* TODO: fix this */
1000 if (png_rtran_ok(png_ptr, 1) == 0)
1001 return;
1002
1003 switch (error_action)
1004 {
1005 case PNG_ERROR_ACTION_NONE:
1006 png_ptr->transformations |= PNG_RGB_TO_GRAY;
1007 break;
1008
1009 case PNG_ERROR_ACTION_WARN:
1010 png_ptr->transformations |= PNG_RGB_TO_GRAY_WARN;
1011 break;
1012
1013 case PNG_ERROR_ACTION_ERROR:
1014 png_ptr->transformations |= PNG_RGB_TO_GRAY_ERR;
1015 break;
1016
1017 default:
1018 png_error(png_ptr, "invalid error action to rgb_to_gray");
1019 }
1020
1021 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1022 #ifdef PNG_READ_EXPAND_SUPPORTED
1023 png_ptr->transformations |= PNG_EXPAND;
1024 #else
1025 {
1026 /* Make this an error in 1.6 because otherwise the application may assume
1027 * that it just worked and get a memory overwrite.
1028 */
1029 png_error(png_ptr,
1030 "Cannot do RGB_TO_GRAY without EXPAND_SUPPORTED");
1031
1032 /* png_ptr->transformations &= ~PNG_RGB_TO_GRAY; */
1033 }
1034 #endif
1035 {
1036 if (red >= 0 && green >= 0 && red + green <= PNG_FP_1)
1037 {
1038 png_uint_16 red_int, green_int;
1039
1040 /* NOTE: this calculation does not round, but this behavior is retained
1041 * for consistency; the inaccuracy is very small. The code here always
1042 * overwrites the coefficients, regardless of whether they have been
1043 * defaulted or set already.
1044 */
1045 red_int = (png_uint_16)(((png_uint_32)red*32768)/100000);
1046 green_int = (png_uint_16)(((png_uint_32)green*32768)/100000);
1047
1048 png_ptr->rgb_to_gray_red_coeff = red_int;
1049 png_ptr->rgb_to_gray_green_coeff = green_int;
1050 png_ptr->rgb_to_gray_coefficients_set = 1;
1051 }
1052
1053 else
1054 {
1055 if (red >= 0 && green >= 0)
1056 png_app_warning(png_ptr,
1057 "ignoring out of range rgb_to_gray coefficients");
1058
1059 /* Use the defaults, from the cHRM chunk if set, else the historical
1060 * values which are close to the sRGB/HDTV/ITU-Rec 709 values. See
1061 * png_do_rgb_to_gray for more discussion of the values. In this case
1062 * the coefficients are not marked as 'set' and are not overwritten if
1063 * something has already provided a default.
1064 */
1065 if (png_ptr->rgb_to_gray_red_coeff == 0 &&
1066 png_ptr->rgb_to_gray_green_coeff == 0)
1067 {
1068 png_ptr->rgb_to_gray_red_coeff = 6968;
1069 png_ptr->rgb_to_gray_green_coeff = 23434;
1070 /* png_ptr->rgb_to_gray_blue_coeff = 2366; */
1071 }
1072 }
1073 }
1074 }
1075
1076 #ifdef PNG_FLOATING_POINT_SUPPORTED
1077 /* Convert a RGB image to a grayscale of the same width. This allows us,
1078 * for example, to convert a 24 bpp RGB image into an 8 bpp grayscale image.
1079 */
1080
1081 void PNGAPI
1082 png_set_rgb_to_gray(png_structrp png_ptr, int error_action, double red,
1083 double green)
1084 {
1085 png_set_rgb_to_gray_fixed(png_ptr, error_action,
1086 png_fixed(png_ptr, red, "rgb to gray red coefficient"),
1087 png_fixed(png_ptr, green, "rgb to gray green coefficient"));
1088 }
1089 #endif /* FLOATING POINT */
1090
1091 #endif /* RGB_TO_GRAY */
1092
1093 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
1094 defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
1095 void PNGAPI
1096 png_set_read_user_transform_fn(png_structrp png_ptr, png_user_transform_ptr
1097 read_user_transform_fn)
1098 {
1099 png_debug(1, "in png_set_read_user_transform_fn");
1100
1101 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
1102 png_ptr->transformations |= PNG_USER_TRANSFORM;
1103 png_ptr->read_user_transform_fn = read_user_transform_fn;
1104 #endif
1105 }
1106 #endif
1107
1108 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
1109 #ifdef PNG_READ_GAMMA_SUPPORTED
1110 /* In the case of gamma transformations only do transformations on images where
1111 * the [file] gamma and screen_gamma are not close reciprocals, otherwise it
1112 * slows things down slightly, and also needlessly introduces small errors.
1113 */
1114 static int /* PRIVATE */
1115 png_gamma_threshold(png_fixed_point screen_gamma, png_fixed_point file_gamma)
1116 {
1117 /* PNG_GAMMA_THRESHOLD is the threshold for performing gamma
1118 * correction as a difference of the overall transform from 1.0
1119 *
1120 * We want to compare the threshold with s*f - 1, if we get
1121 * overflow here it is because of wacky gamma values so we
1122 * turn on processing anyway.
1123 */
1124 png_fixed_point gtest;
1125 return !png_muldiv(>est, screen_gamma, file_gamma, PNG_FP_1) ||
1126 png_gamma_significant(gtest);
1127 }
1128 #endif
1129
1130 /* Initialize everything needed for the read. This includes modifying
1131 * the palette.
1132 */
1133
1134 /* For the moment 'png_init_palette_transformations' and
1135 * 'png_init_rgb_transformations' only do some flag canceling optimizations.
1136 * The intent is that these two routines should have palette or rgb operations
1137 * extracted from 'png_init_read_transformations'.
1138 */
1139 static void /* PRIVATE */
1140 png_init_palette_transformations(png_structrp png_ptr)
1141 {
1142 /* Called to handle the (input) palette case. In png_do_read_transformations
1143 * the first step is to expand the palette if requested, so this code must
1144 * take care to only make changes that are invariant with respect to the
1145 * palette expansion, or only do them if there is no expansion.
1146 *
1147 * STRIP_ALPHA has already been handled in the caller (by setting num_trans
1148 * to 0.)
1149 */
1150 int input_has_alpha = 0;
1151 int input_has_transparency = 0;
1152
1153 if (png_ptr->num_trans > 0)
1154 {
1155 int i;
1156
1157 /* Ignore if all the entries are opaque (unlikely!) */
1158 for (i=0; i<png_ptr->num_trans; ++i)
1159 {
1160 if (png_ptr->trans_alpha[i] == 255)
1161 continue;
1162 else if (png_ptr->trans_alpha[i] == 0)
1163 input_has_transparency = 1;
1164 else
1165 {
1166 input_has_transparency = 1;
1167 input_has_alpha = 1;
1168 break;
1169 }
1170 }
1171 }
1172
1173 /* If no alpha we can optimize. */
1174 if (input_has_alpha == 0)
1175 {
1176 /* Any alpha means background and associative alpha processing is
1177 * required, however if the alpha is 0 or 1 throughout OPTIMIZE_ALPHA
1178 * and ENCODE_ALPHA are irrelevant.
1179 */
1180 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1181 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1182
1183 if (input_has_transparency == 0)
1184 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
1185 }
1186
1187 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1188 /* png_set_background handling - deals with the complexity of whether the
1189 * background color is in the file format or the screen format in the case
1190 * where an 'expand' will happen.
1191 */
1192
1193 /* The following code cannot be entered in the alpha pre-multiplication case
1194 * because PNG_BACKGROUND_EXPAND is cancelled below.
1195 */
1196 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0 &&
1197 (png_ptr->transformations & PNG_EXPAND) != 0)
1198 {
1199 {
1200 png_ptr->background.red =
1201 png_ptr->palette[png_ptr->background.index].red;
1202 png_ptr->background.green =
1203 png_ptr->palette[png_ptr->background.index].green;
1204 png_ptr->background.blue =
1205 png_ptr->palette[png_ptr->background.index].blue;
1206
1207 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
1208 if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0)
1209 {
1210 if ((png_ptr->transformations & PNG_EXPAND_tRNS) == 0)
1211 {
1212 /* Invert the alpha channel (in tRNS) unless the pixels are
1213 * going to be expanded, in which case leave it for later
1214 */
1215 int i, istop = png_ptr->num_trans;
1216
1217 for (i = 0; i < istop; i++)
1218 png_ptr->trans_alpha[i] =
1219 (png_byte)(255 - png_ptr->trans_alpha[i]);
1220 }
1221 }
1222 #endif /* READ_INVERT_ALPHA */
1223 }
1224 } /* background expand and (therefore) no alpha association. */
1225 #endif /* READ_EXPAND && READ_BACKGROUND */
1226 }
1227
1228 static void /* PRIVATE */
1229 png_init_rgb_transformations(png_structrp png_ptr)
1230 {
1231 /* Added to libpng-1.5.4: check the color type to determine whether there
1232 * is any alpha or transparency in the image and simply cancel the
1233 * background and alpha mode stuff if there isn't.
1234 */
1235 int input_has_alpha = (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0;
1236 int input_has_transparency = png_ptr->num_trans > 0;
1237
1238 /* If no alpha we can optimize. */
1239 if (input_has_alpha == 0)
1240 {
1241 /* Any alpha means background and associative alpha processing is
1242 * required, however if the alpha is 0 or 1 throughout OPTIMIZE_ALPHA
1243 * and ENCODE_ALPHA are irrelevant.
1244 */
1245 # ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1246 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1247 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1248 # endif
1249
1250 if (input_has_transparency == 0)
1251 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
1252 }
1253
1254 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1255 /* png_set_background handling - deals with the complexity of whether the
1256 * background color is in the file format or the screen format in the case
1257 * where an 'expand' will happen.
1258 */
1259
1260 /* The following code cannot be entered in the alpha pre-multiplication case
1261 * because PNG_BACKGROUND_EXPAND is cancelled below.
1262 */
1263 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0 &&
1264 (png_ptr->transformations & PNG_EXPAND) != 0 &&
1265 (png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
1266 /* i.e., GRAY or GRAY_ALPHA */
1267 {
1268 {
1269 /* Expand background and tRNS chunks */
1270 int gray = png_ptr->background.gray;
1271 int trans_gray = png_ptr->trans_color.gray;
1272
1273 switch (png_ptr->bit_depth)
1274 {
1275 case 1:
1276 gray *= 0xff;
1277 trans_gray *= 0xff;
1278 break;
1279
1280 case 2:
1281 gray *= 0x55;
1282 trans_gray *= 0x55;
1283 break;
1284
1285 case 4:
1286 gray *= 0x11;
1287 trans_gray *= 0x11;
1288 break;
1289
1290 default:
1291
1292 case 8:
1293 /* FALLTHROUGH */ /* (Already 8 bits) */
1294
1295 case 16:
1296 /* Already a full 16 bits */
1297 break;
1298 }
1299
1300 png_ptr->background.red = png_ptr->background.green =
1301 png_ptr->background.blue = (png_uint_16)gray;
1302
1303 if ((png_ptr->transformations & PNG_EXPAND_tRNS) == 0)
1304 {
1305 png_ptr->trans_color.red = png_ptr->trans_color.green =
1306 png_ptr->trans_color.blue = (png_uint_16)trans_gray;
1307 }
1308 }
1309 } /* background expand and (therefore) no alpha association. */
1310 #endif /* READ_EXPAND && READ_BACKGROUND */
1311 }
1312
1313 void /* PRIVATE */
1314 png_init_read_transformations(png_structrp png_ptr)
1315 {
1316 png_debug(1, "in png_init_read_transformations");
1317
1318 /* This internal function is called from png_read_start_row in pngrutil.c
1319 * and it is called before the 'rowbytes' calculation is done, so the code
1320 * in here can change or update the transformations flags.
1321 *
1322 * First do updates that do not depend on the details of the PNG image data
1323 * being processed.
1324 */
1325
1326 #ifdef PNG_READ_GAMMA_SUPPORTED
1327 /* Prior to 1.5.4 these tests were performed from png_set_gamma, 1.5.4 adds
1328 * png_set_alpha_mode and this is another source for a default file gamma so
1329 * the test needs to be performed later - here. In addition prior to 1.5.4
1330 * the tests were repeated for the PALETTE color type here - this is no
1331 * longer necessary (and doesn't seem to have been necessary before.)
1332 */
1333 {
1334 /* The following temporary indicates if overall gamma correction is
1335 * required.
1336 */
1337 int gamma_correction = 0;
1338
1339 if (png_ptr->colorspace.gamma != 0) /* has been set */
1340 {
1341 if (png_ptr->screen_gamma != 0) /* screen set too */
1342 gamma_correction = png_gamma_threshold(png_ptr->colorspace.gamma,
1343 png_ptr->screen_gamma);
1344
1345 else
1346 /* Assume the output matches the input; a long time default behavior
1347 * of libpng, although the standard has nothing to say about this.
1348 */
1349 png_ptr->screen_gamma = png_reciprocal(png_ptr->colorspace.gamma);
1350 }
1351
1352 else if (png_ptr->screen_gamma != 0)
1353 /* The converse - assume the file matches the screen, note that this
1354 * perhaps undesirable default can (from 1.5.4) be changed by calling
1355 * png_set_alpha_mode (even if the alpha handling mode isn't required
1356 * or isn't changed from the default.)
1357 */
1358 png_ptr->colorspace.gamma = png_reciprocal(png_ptr->screen_gamma);
1359
1360 else /* neither are set */
1361 /* Just in case the following prevents any processing - file and screen
1362 * are both assumed to be linear and there is no way to introduce a
1363 * third gamma value other than png_set_background with 'UNIQUE', and,
1364 * prior to 1.5.4
1365 */
1366 png_ptr->screen_gamma = png_ptr->colorspace.gamma = PNG_FP_1;
1367
1368 /* We have a gamma value now. */
1369 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
1370
1371 /* Now turn the gamma transformation on or off as appropriate. Notice
1372 * that PNG_GAMMA just refers to the file->screen correction. Alpha
1373 * composition may independently cause gamma correction because it needs
1374 * linear data (e.g. if the file has a gAMA chunk but the screen gamma
1375 * hasn't been specified.) In any case this flag may get turned off in
1376 * the code immediately below if the transform can be handled outside the
1377 * row loop.
1378 */
1379 if (gamma_correction != 0)
1380 png_ptr->transformations |= PNG_GAMMA;
1381
1382 else
1383 png_ptr->transformations &= ~PNG_GAMMA;
1384 }
1385 #endif
1386
1387 /* Certain transformations have the effect of preventing other
1388 * transformations that happen afterward in png_do_read_transformations;
1389 * resolve the interdependencies here. From the code of
1390 * png_do_read_transformations the order is:
1391 *
1392 * 1) PNG_EXPAND (including PNG_EXPAND_tRNS)
1393 * 2) PNG_STRIP_ALPHA (if no compose)
1394 * 3) PNG_RGB_TO_GRAY
1395 * 4) PNG_GRAY_TO_RGB iff !PNG_BACKGROUND_IS_GRAY
1396 * 5) PNG_COMPOSE
1397 * 6) PNG_GAMMA
1398 * 7) PNG_STRIP_ALPHA (if compose)
1399 * 8) PNG_ENCODE_ALPHA
1400 * 9) PNG_SCALE_16_TO_8
1401 * 10) PNG_16_TO_8
1402 * 11) PNG_QUANTIZE (converts to palette)
1403 * 12) PNG_EXPAND_16
1404 * 13) PNG_GRAY_TO_RGB iff PNG_BACKGROUND_IS_GRAY
1405 * 14) PNG_INVERT_MONO
1406 * 15) PNG_INVERT_ALPHA
1407 * 16) PNG_SHIFT
1408 * 17) PNG_PACK
1409 * 18) PNG_BGR
1410 * 19) PNG_PACKSWAP
1411 * 20) PNG_FILLER (includes PNG_ADD_ALPHA)
1412 * 21) PNG_SWAP_ALPHA
1413 * 22) PNG_SWAP_BYTES
1414 * 23) PNG_USER_TRANSFORM [must be last]
1415 */
1416 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
1417 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
1418 (png_ptr->transformations & PNG_COMPOSE) == 0)
1419 {
1420 /* Stripping the alpha channel happens immediately after the 'expand'
1421 * transformations, before all other transformation, so it cancels out
1422 * the alpha handling. It has the side effect negating the effect of
1423 * PNG_EXPAND_tRNS too:
1424 */
1425 png_ptr->transformations &= ~(PNG_BACKGROUND_EXPAND | PNG_ENCODE_ALPHA |
1426 PNG_EXPAND_tRNS);
1427 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1428
1429 /* Kill the tRNS chunk itself too. Prior to 1.5.4 this did not happen
1430 * so transparency information would remain just so long as it wasn't
1431 * expanded. This produces unexpected API changes if the set of things
1432 * that do PNG_EXPAND_tRNS changes (perfectly possible given the
1433 * documentation - which says ask for what you want, accept what you
1434 * get.) This makes the behavior consistent from 1.5.4:
1435 */
1436 png_ptr->num_trans = 0;
1437 }
1438 #endif /* STRIP_ALPHA supported, no COMPOSE */
1439
1440 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1441 /* If the screen gamma is about 1.0 then the OPTIMIZE_ALPHA and ENCODE_ALPHA
1442 * settings will have no effect.
1443 */
1444 if (png_gamma_significant(png_ptr->screen_gamma) == 0)
1445 {
1446 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
1447 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
1448 }
1449 #endif
1450
1451 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1452 /* Make sure the coefficients for the rgb to gray conversion are set
1453 * appropriately.
1454 */
1455 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
1456 png_colorspace_set_rgb_coefficients(png_ptr);
1457 #endif
1458
1459 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
1460 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
1461 /* Detect gray background and attempt to enable optimization for
1462 * gray --> RGB case.
1463 *
1464 * Note: if PNG_BACKGROUND_EXPAND is set and color_type is either RGB or
1465 * RGB_ALPHA (in which case need_expand is superfluous anyway), the
1466 * background color might actually be gray yet not be flagged as such.
1467 * This is not a problem for the current code, which uses
1468 * PNG_BACKGROUND_IS_GRAY only to decide when to do the
1469 * png_do_gray_to_rgb() transformation.
1470 *
1471 * TODO: this code needs to be revised to avoid the complexity and
1472 * interdependencies. The color type of the background should be recorded in
1473 * png_set_background, along with the bit depth, then the code has a record
1474 * of exactly what color space the background is currently in.
1475 */
1476 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0)
1477 {
1478 /* PNG_BACKGROUND_EXPAND: the background is in the file color space, so if
1479 * the file was grayscale the background value is gray.
1480 */
1481 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
1482 png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
1483 }
1484
1485 else if ((png_ptr->transformations & PNG_COMPOSE) != 0)
1486 {
1487 /* PNG_COMPOSE: png_set_background was called with need_expand false,
1488 * so the color is in the color space of the output or png_set_alpha_mode
1489 * was called and the color is black. Ignore RGB_TO_GRAY because that
1490 * happens before GRAY_TO_RGB.
1491 */
1492 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
1493 {
1494 if (png_ptr->background.red == png_ptr->background.green &&
1495 png_ptr->background.red == png_ptr->background.blue)
1496 {
1497 png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
1498 png_ptr->background.gray = png_ptr->background.red;
1499 }
1500 }
1501 }
1502 #endif /* READ_EXPAND && READ_BACKGROUND */
1503 #endif /* READ_GRAY_TO_RGB */
1504
1505 /* For indexed PNG data (PNG_COLOR_TYPE_PALETTE) many of the transformations
1506 * can be performed directly on the palette, and some (such as rgb to gray)
1507 * can be optimized inside the palette. This is particularly true of the
1508 * composite (background and alpha) stuff, which can be pretty much all done
1509 * in the palette even if the result is expanded to RGB or gray afterward.
1510 *
1511 * NOTE: this is Not Yet Implemented, the code behaves as in 1.5.1 and
1512 * earlier and the palette stuff is actually handled on the first row. This
1513 * leads to the reported bug that the palette returned by png_get_PLTE is not
1514 * updated.
1515 */
1516 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1517 png_init_palette_transformations(png_ptr);
1518
1519 else
1520 png_init_rgb_transformations(png_ptr);
1521
1522 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
1523 defined(PNG_READ_EXPAND_16_SUPPORTED)
1524 if ((png_ptr->transformations & PNG_EXPAND_16) != 0 &&
1525 (png_ptr->transformations & PNG_COMPOSE) != 0 &&
1526 (png_ptr->transformations & PNG_BACKGROUND_EXPAND) == 0 &&
1527 png_ptr->bit_depth != 16)
1528 {
1529 /* TODO: fix this. Because the expand_16 operation is after the compose
1530 * handling the background color must be 8, not 16, bits deep, but the
1531 * application will supply a 16-bit value so reduce it here.
1532 *
1533 * The PNG_BACKGROUND_EXPAND code above does not expand to 16 bits at
1534 * present, so that case is ok (until do_expand_16 is moved.)
1535 *
1536 * NOTE: this discards the low 16 bits of the user supplied background
1537 * color, but until expand_16 works properly there is no choice!
1538 */
1539 # define CHOP(x) (x)=((png_uint_16)PNG_DIV257(x))
1540 CHOP(png_ptr->background.red);
1541 CHOP(png_ptr->background.green);
1542 CHOP(png_ptr->background.blue);
1543 CHOP(png_ptr->background.gray);
1544 # undef CHOP
1545 }
1546 #endif /* READ_BACKGROUND && READ_EXPAND_16 */
1547
1548 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
1549 (defined(PNG_READ_SCALE_16_TO_8_SUPPORTED) || \
1550 defined(PNG_READ_STRIP_16_TO_8_SUPPORTED))
1551 if ((png_ptr->transformations & (PNG_16_TO_8|PNG_SCALE_16_TO_8)) != 0 &&
1552 (png_ptr->transformations & PNG_COMPOSE) != 0 &&
1553 (png_ptr->transformations & PNG_BACKGROUND_EXPAND) == 0 &&
1554 png_ptr->bit_depth == 16)
1555 {
1556 /* On the other hand, if a 16-bit file is to be reduced to 8-bits per
1557 * component this will also happen after PNG_COMPOSE and so the background
1558 * color must be pre-expanded here.
1559 *
1560 * TODO: fix this too.
1561 */
1562 png_ptr->background.red = (png_uint_16)(png_ptr->background.red * 257);
1563 png_ptr->background.green =
1564 (png_uint_16)(png_ptr->background.green * 257);
1565 png_ptr->background.blue = (png_uint_16)(png_ptr->background.blue * 257);
1566 png_ptr->background.gray = (png_uint_16)(png_ptr->background.gray * 257);
1567 }
1568 #endif
1569
1570 /* NOTE: below 'PNG_READ_ALPHA_MODE_SUPPORTED' is presumed to also enable the
1571 * background support (see the comments in scripts/pnglibconf.dfa), this
1572 * allows pre-multiplication of the alpha channel to be implemented as
1573 * compositing on black. This is probably sub-optimal and has been done in
1574 * 1.5.4 betas simply to enable external critique and testing (i.e. to
1575 * implement the new API quickly, without lots of internal changes.)
1576 */
1577
1578 #ifdef PNG_READ_GAMMA_SUPPORTED
1579 # ifdef PNG_READ_BACKGROUND_SUPPORTED
1580 /* Includes ALPHA_MODE */
1581 png_ptr->background_1 = png_ptr->background;
1582 # endif
1583
1584 /* This needs to change - in the palette image case a whole set of tables are
1585 * built when it would be quicker to just calculate the correct value for
1586 * each palette entry directly. Also, the test is too tricky - why check
1587 * PNG_RGB_TO_GRAY if PNG_GAMMA is not set? The answer seems to be that
1588 * PNG_GAMMA is cancelled even if the gamma is known? The test excludes the
1589 * PNG_COMPOSE case, so apparently if there is no *overall* gamma correction
1590 * the gamma tables will not be built even if composition is required on a
1591 * gamma encoded value.
1592 *
1593 * In 1.5.4 this is addressed below by an additional check on the individual
1594 * file gamma - if it is not 1.0 both RGB_TO_GRAY and COMPOSE need the
1595 * tables.
1596 */
1597 if ((png_ptr->transformations & PNG_GAMMA) != 0 ||
1598 ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0 &&
1599 (png_gamma_significant(png_ptr->colorspace.gamma) != 0 ||
1600 png_gamma_significant(png_ptr->screen_gamma) != 0)) ||
1601 ((png_ptr->transformations & PNG_COMPOSE) != 0 &&
1602 (png_gamma_significant(png_ptr->colorspace.gamma) != 0 ||
1603 png_gamma_significant(png_ptr->screen_gamma) != 0
1604 # ifdef PNG_READ_BACKGROUND_SUPPORTED
1605 || (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_UNIQUE &&
1606 png_gamma_significant(png_ptr->background_gamma) != 0)
1607 # endif
1608 )) || ((png_ptr->transformations & PNG_ENCODE_ALPHA) != 0 &&
1609 png_gamma_significant(png_ptr->screen_gamma) != 0))
1610 {
1611 png_build_gamma_table(png_ptr, png_ptr->bit_depth);
1612
1613 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1614 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
1615 {
1616 /* Issue a warning about this combination: because RGB_TO_GRAY is
1617 * optimized to do the gamma transform if present yet do_background has
1618 * to do the same thing if both options are set a
1619 * double-gamma-correction happens. This is true in all versions of
1620 * libpng to date.
1621 */
1622 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
1623 png_warning(png_ptr,
1624 "libpng does not support gamma+background+rgb_to_gray");
1625
1626 if ((png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) != 0)
1627 {
1628 /* We don't get to here unless there is a tRNS chunk with non-opaque
1629 * entries - see the checking code at the start of this function.
1630 */
1631 png_color back, back_1;
1632 png_colorp palette = png_ptr->palette;
1633 int num_palette = png_ptr->num_palette;
1634 int i;
1635 if (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_FILE)
1636 {
1637
1638 back.red = png_ptr->gamma_table[png_ptr->background.red];
1639 back.green = png_ptr->gamma_table[png_ptr->background.green];
1640 back.blue = png_ptr->gamma_table[png_ptr->background.blue];
1641
1642 back_1.red = png_ptr->gamma_to_1[png_ptr->background.red];
1643 back_1.green = png_ptr->gamma_to_1[png_ptr->background.green];
1644 back_1.blue = png_ptr->gamma_to_1[png_ptr->background.blue];
1645 }
1646 else
1647 {
1648 png_fixed_point g, gs;
1649
1650 switch (png_ptr->background_gamma_type)
1651 {
1652 case PNG_BACKGROUND_GAMMA_SCREEN:
1653 g = (png_ptr->screen_gamma);
1654 gs = PNG_FP_1;
1655 break;
1656
1657 case PNG_BACKGROUND_GAMMA_FILE:
1658 g = png_reciprocal(png_ptr->colorspace.gamma);
1659 gs = png_reciprocal2(png_ptr->colorspace.gamma,
1660 png_ptr->screen_gamma);
1661 break;
1662
1663 case PNG_BACKGROUND_GAMMA_UNIQUE:
1664 g = png_reciprocal(png_ptr->background_gamma);
1665 gs = png_reciprocal2(png_ptr->background_gamma,
1666 png_ptr->screen_gamma);
1667 break;
1668 default:
1669 g = PNG_FP_1; /* back_1 */
1670 gs = PNG_FP_1; /* back */
1671 break;
1672 }
1673
1674 if (png_gamma_significant(gs) != 0)
1675 {
1676 back.red = png_gamma_8bit_correct(png_ptr->background.red,
1677 gs);
1678 back.green = png_gamma_8bit_correct(png_ptr->background.green,
1679 gs);
1680 back.blue = png_gamma_8bit_correct(png_ptr->background.blue,
1681 gs);
1682 }
1683
1684 else
1685 {
1686 back.red = (png_byte)png_ptr->background.red;
1687 back.green = (png_byte)png_ptr->background.green;
1688 back.blue = (png_byte)png_ptr->background.blue;
1689 }
1690
1691 if (png_gamma_significant(g) != 0)
1692 {
1693 back_1.red = png_gamma_8bit_correct(png_ptr->background.red,
1694 g);
1695 back_1.green = png_gamma_8bit_correct(
1696 png_ptr->background.green, g);
1697 back_1.blue = png_gamma_8bit_correct(png_ptr->background.blue,
1698 g);
1699 }
1700
1701 else
1702 {
1703 back_1.red = (png_byte)png_ptr->background.red;
1704 back_1.green = (png_byte)png_ptr->background.green;
1705 back_1.blue = (png_byte)png_ptr->background.blue;
1706 }
1707 }
1708
1709 for (i = 0; i < num_palette; i++)
1710 {
1711 if (i < (int)png_ptr->num_trans &&
1712 png_ptr->trans_alpha[i] != 0xff)
1713 {
1714 if (png_ptr->trans_alpha[i] == 0)
1715 {
1716 palette[i] = back;
1717 }
1718 else /* if (png_ptr->trans_alpha[i] != 0xff) */
1719 {
1720 png_byte v, w;
1721
1722 v = png_ptr->gamma_to_1[palette[i].red];
1723 png_composite(w, v, png_ptr->trans_alpha[i], back_1.red);
1724 palette[i].red = png_ptr->gamma_from_1[w];
1725
1726 v = png_ptr->gamma_to_1[palette[i].green];
1727 png_composite(w, v, png_ptr->trans_alpha[i], back_1.green);
1728 palette[i].green = png_ptr->gamma_from_1[w];
1729
1730 v = png_ptr->gamma_to_1[palette[i].blue];
1731 png_composite(w, v, png_ptr->trans_alpha[i], back_1.blue);
1732 palette[i].blue = png_ptr->gamma_from_1[w];
1733 }
1734 }
1735 else
1736 {
1737 palette[i].red = png_ptr->gamma_table[palette[i].red];
1738 palette[i].green = png_ptr->gamma_table[palette[i].green];
1739 palette[i].blue = png_ptr->gamma_table[palette[i].blue];
1740 }
1741 }
1742
1743 /* Prevent the transformations being done again.
1744 *
1745 * NOTE: this is highly dubious; it removes the transformations in
1746 * place. This seems inconsistent with the general treatment of the
1747 * transformations elsewhere.
1748 */
1749 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_GAMMA);
1750 } /* color_type == PNG_COLOR_TYPE_PALETTE */
1751
1752 /* if (png_ptr->background_gamma_type!=PNG_BACKGROUND_GAMMA_UNKNOWN) */
1753 else /* color_type != PNG_COLOR_TYPE_PALETTE */
1754 {
1755 int gs_sig, g_sig;
1756 png_fixed_point g = PNG_FP_1; /* Correction to linear */
1757 png_fixed_point gs = PNG_FP_1; /* Correction to screen */
1758
1759 switch (png_ptr->background_gamma_type)
1760 {
1761 case PNG_BACKGROUND_GAMMA_SCREEN:
1762 g = png_ptr->screen_gamma;
1763 /* gs = PNG_FP_1; */
1764 break;
1765
1766 case PNG_BACKGROUND_GAMMA_FILE:
1767 g = png_reciprocal(png_ptr->colorspace.gamma);
1768 gs = png_reciprocal2(png_ptr->colorspace.gamma,
1769 png_ptr->screen_gamma);
1770 break;
1771
1772 case PNG_BACKGROUND_GAMMA_UNIQUE:
1773 g = png_reciprocal(png_ptr->background_gamma);
1774 gs = png_reciprocal2(png_ptr->background_gamma,
1775 png_ptr->screen_gamma);
1776 break;
1777
1778 default:
1779 png_error(png_ptr, "invalid background gamma type");
1780 }
1781
1782 g_sig = png_gamma_significant(g);
1783 gs_sig = png_gamma_significant(gs);
1784
1785 if (g_sig != 0)
1786 png_ptr->background_1.gray = png_gamma_correct(png_ptr,
1787 png_ptr->background.gray, g);
1788
1789 if (gs_sig != 0)
1790 png_ptr->background.gray = png_gamma_correct(png_ptr,
1791 png_ptr->background.gray, gs);
1792
1793 if ((png_ptr->background.red != png_ptr->background.green) ||
1794 (png_ptr->background.red != png_ptr->background.blue) ||
1795 (png_ptr->background.red != png_ptr->background.gray))
1796 {
1797 /* RGB or RGBA with color background */
1798 if (g_sig != 0)
1799 {
1800 png_ptr->background_1.red = png_gamma_correct(png_ptr,
1801 png_ptr->background.red, g);
1802
1803 png_ptr->background_1.green = png_gamma_correct(png_ptr,
1804 png_ptr->background.green, g);
1805
1806 png_ptr->background_1.blue = png_gamma_correct(png_ptr,
1807 png_ptr->background.blue, g);
1808 }
1809
1810 if (gs_sig != 0)
1811 {
1812 png_ptr->background.red = png_gamma_correct(png_ptr,
1813 png_ptr->background.red, gs);
1814
1815 png_ptr->background.green = png_gamma_correct(png_ptr,
1816 png_ptr->background.green, gs);
1817
1818 png_ptr->background.blue = png_gamma_correct(png_ptr,
1819 png_ptr->background.blue, gs);
1820 }
1821 }
1822
1823 else
1824 {
1825 /* GRAY, GRAY ALPHA, RGB, or RGBA with gray background */
1826 png_ptr->background_1.red = png_ptr->background_1.green
1827 = png_ptr->background_1.blue = png_ptr->background_1.gray;
1828
1829 png_ptr->background.red = png_ptr->background.green
1830 = png_ptr->background.blue = png_ptr->background.gray;
1831 }
1832
1833 /* The background is now in screen gamma: */
1834 png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_SCREEN;
1835 } /* color_type != PNG_COLOR_TYPE_PALETTE */
1836 }/* png_ptr->transformations & PNG_BACKGROUND */
1837
1838 else
1839 /* Transformation does not include PNG_BACKGROUND */
1840 #endif /* READ_BACKGROUND */
1841 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE
1842 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1843 /* RGB_TO_GRAY needs to have non-gamma-corrected values! */
1844 && ((png_ptr->transformations & PNG_EXPAND) == 0 ||
1845 (png_ptr->transformations & PNG_RGB_TO_GRAY) == 0)
1846 #endif
1847 )
1848 {
1849 png_colorp palette = png_ptr->palette;
1850 int num_palette = png_ptr->num_palette;
1851 int i;
1852
1853 /* NOTE: there are other transformations that should probably be in
1854 * here too.
1855 */
1856 for (i = 0; i < num_palette; i++)
1857 {
1858 palette[i].red = png_ptr->gamma_table[palette[i].red];
1859 palette[i].green = png_ptr->gamma_table[palette[i].green];
1860 palette[i].blue = png_ptr->gamma_table[palette[i].blue];
1861 }
1862
1863 /* Done the gamma correction. */
1864 png_ptr->transformations &= ~PNG_GAMMA;
1865 } /* color_type == PALETTE && !PNG_BACKGROUND transformation */
1866 }
1867 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1868 else
1869 #endif
1870 #endif /* READ_GAMMA */
1871
1872 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1873 /* No GAMMA transformation (see the hanging else 4 lines above) */
1874 if ((png_ptr->transformations & PNG_COMPOSE) != 0 &&
1875 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
1876 {
1877 int i;
1878 int istop = (int)png_ptr->num_trans;
1879 png_color back;
1880 png_colorp palette = png_ptr->palette;
1881
1882 back.red = (png_byte)png_ptr->background.red;
1883 back.green = (png_byte)png_ptr->background.green;
1884 back.blue = (png_byte)png_ptr->background.blue;
1885
1886 for (i = 0; i < istop; i++)
1887 {
1888 if (png_ptr->trans_alpha[i] == 0)
1889 {
1890 palette[i] = back;
1891 }
1892
1893 else if (png_ptr->trans_alpha[i] != 0xff)
1894 {
1895 /* The png_composite() macro is defined in png.h */
1896 png_composite(palette[i].red, palette[i].red,
1897 png_ptr->trans_alpha[i], back.red);
1898
1899 png_composite(palette[i].green, palette[i].green,
1900 png_ptr->trans_alpha[i], back.green);
1901
1902 png_composite(palette[i].blue, palette[i].blue,
1903 png_ptr->trans_alpha[i], back.blue);
1904 }
1905 }
1906
1907 png_ptr->transformations &= ~PNG_COMPOSE;
1908 }
1909 #endif /* READ_BACKGROUND */
1910
1911 #ifdef PNG_READ_SHIFT_SUPPORTED
1912 if ((png_ptr->transformations & PNG_SHIFT) != 0 &&
1913 (png_ptr->transformations & PNG_EXPAND) == 0 &&
1914 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
1915 {
1916 int i;
1917 int istop = png_ptr->num_palette;
1918 int shift = 8 - png_ptr->sig_bit.red;
1919
1920 png_ptr->transformations &= ~PNG_SHIFT;
1921
1922 /* significant bits can be in the range 1 to 7 for a meaningful result, if
1923 * the number of significant bits is 0 then no shift is done (this is an
1924 * error condition which is silently ignored.)
1925 */
1926 if (shift > 0 && shift < 8)
1927 for (i=0; i<istop; ++i)
1928 {
1929 int component = png_ptr->palette[i].red;
1930
1931 component >>= shift;
1932 png_ptr->palette[i].red = (png_byte)component;
1933 }
1934
1935 shift = 8 - png_ptr->sig_bit.green;
1936 if (shift > 0 && shift < 8)
1937 for (i=0; i<istop; ++i)
1938 {
1939 int component = png_ptr->palette[i].green;
1940
1941 component >>= shift;
1942 png_ptr->palette[i].green = (png_byte)component;
1943 }
1944
1945 shift = 8 - png_ptr->sig_bit.blue;
1946 if (shift > 0 && shift < 8)
1947 for (i=0; i<istop; ++i)
1948 {
1949 int component = png_ptr->palette[i].blue;
1950
1951 component >>= shift;
1952 png_ptr->palette[i].blue = (png_byte)component;
1953 }
1954 }
1955 #endif /* READ_SHIFT */
1956 }
1957
1958 /* Modify the info structure to reflect the transformations. The
1959 * info should be updated so a PNG file could be written with it,
1960 * assuming the transformations result in valid PNG data.
1961 */
1962 void /* PRIVATE */
1963 png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr)
1964 {
1965 png_debug(1, "in png_read_transform_info");
1966
1967 #ifdef PNG_READ_EXPAND_SUPPORTED
1968 if ((png_ptr->transformations & PNG_EXPAND) != 0)
1969 {
1970 if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
1971 {
1972 /* This check must match what actually happens in
1973 * png_do_expand_palette; if it ever checks the tRNS chunk to see if
1974 * it is all opaque we must do the same (at present it does not.)
1975 */
1976 if (png_ptr->num_trans > 0)
1977 info_ptr->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
1978
1979 else
1980 info_ptr->color_type = PNG_COLOR_TYPE_RGB;
1981
1982 info_ptr->bit_depth = 8;
1983 info_ptr->num_trans = 0;
1984
1985 if (png_ptr->palette == NULL)
1986 png_error (png_ptr, "Palette is NULL in indexed image");
1987 }
1988 else
1989 {
1990 if (png_ptr->num_trans != 0)
1991 {
1992 if ((png_ptr->transformations & PNG_EXPAND_tRNS) != 0)
1993 info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
1994 }
1995 if (info_ptr->bit_depth < 8)
1996 info_ptr->bit_depth = 8;
1997
1998 info_ptr->num_trans = 0;
1999 }
2000 }
2001 #endif
2002
2003 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
2004 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
2005 /* The following is almost certainly wrong unless the background value is in
2006 * the screen space!
2007 */
2008 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
2009 info_ptr->background = png_ptr->background;
2010 #endif
2011
2012 #ifdef PNG_READ_GAMMA_SUPPORTED
2013 /* The following used to be conditional on PNG_GAMMA (prior to 1.5.4),
2014 * however it seems that the code in png_init_read_transformations, which has
2015 * been called before this from png_read_update_info->png_read_start_row
2016 * sometimes does the gamma transform and cancels the flag.
2017 *
2018 * TODO: this looks wrong; the info_ptr should end up with a gamma equal to
2019 * the screen_gamma value. The following probably results in weirdness if
2020 * the info_ptr is used by the app after the rows have been read.
2021 */
2022 info_ptr->colorspace.gamma = png_ptr->colorspace.gamma;
2023 #endif
2024
2025 if (info_ptr->bit_depth == 16)
2026 {
2027 # ifdef PNG_READ_16BIT_SUPPORTED
2028 # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2029 if ((png_ptr->transformations & PNG_SCALE_16_TO_8) != 0)
2030 info_ptr->bit_depth = 8;
2031 # endif
2032
2033 # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2034 if ((png_ptr->transformations & PNG_16_TO_8) != 0)
2035 info_ptr->bit_depth = 8;
2036 # endif
2037
2038 # else
2039 /* No 16-bit support: force chopping 16-bit input down to 8, in this case
2040 * the app program can chose if both APIs are available by setting the
2041 * correct scaling to use.
2042 */
2043 # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2044 /* For compatibility with previous versions use the strip method by
2045 * default. This code works because if PNG_SCALE_16_TO_8 is already
2046 * set the code below will do that in preference to the chop.
2047 */
2048 png_ptr->transformations |= PNG_16_TO_8;
2049 info_ptr->bit_depth = 8;
2050 # else
2051
2052 # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2053 png_ptr->transformations |= PNG_SCALE_16_TO_8;
2054 info_ptr->bit_depth = 8;
2055 # else
2056
2057 CONFIGURATION ERROR: you must enable at least one 16 to 8 method
2058 # endif
2059 # endif
2060 #endif /* !READ_16BIT */
2061 }
2062
2063 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
2064 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
2065 info_ptr->color_type = (png_byte)(info_ptr->color_type |
2066 PNG_COLOR_MASK_COLOR);
2067 #endif
2068
2069 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2070 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
2071 info_ptr->color_type = (png_byte)(info_ptr->color_type &
2072 ~PNG_COLOR_MASK_COLOR);
2073 #endif
2074
2075 #ifdef PNG_READ_QUANTIZE_SUPPORTED
2076 if ((png_ptr->transformations & PNG_QUANTIZE) != 0)
2077 {
2078 if (((info_ptr->color_type == PNG_COLOR_TYPE_RGB) ||
2079 (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)) &&
2080 png_ptr->palette_lookup != 0 && info_ptr->bit_depth == 8)
2081 {
2082 info_ptr->color_type = PNG_COLOR_TYPE_PALETTE;
2083 }
2084 }
2085 #endif
2086
2087 #ifdef PNG_READ_EXPAND_16_SUPPORTED
2088 if ((png_ptr->transformations & PNG_EXPAND_16) != 0 &&
2089 info_ptr->bit_depth == 8 &&
2090 info_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
2091 {
2092 info_ptr->bit_depth = 16;
2093 }
2094 #endif
2095
2096 #ifdef PNG_READ_PACK_SUPPORTED
2097 if ((png_ptr->transformations & PNG_PACK) != 0 &&
2098 (info_ptr->bit_depth < 8))
2099 info_ptr->bit_depth = 8;
2100 #endif
2101
2102 if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
2103 info_ptr->channels = 1;
2104
2105 else if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
2106 info_ptr->channels = 3;
2107
2108 else
2109 info_ptr->channels = 1;
2110
2111 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
2112 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0)
2113 {
2114 info_ptr->color_type = (png_byte)(info_ptr->color_type &
2115 ~PNG_COLOR_MASK_ALPHA);
2116 info_ptr->num_trans = 0;
2117 }
2118 #endif
2119
2120 if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
2121 info_ptr->channels++;
2122
2123 #ifdef PNG_READ_FILLER_SUPPORTED
2124 /* STRIP_ALPHA and FILLER allowed: MASK_ALPHA bit stripped above */
2125 if ((png_ptr->transformations & PNG_FILLER) != 0 &&
2126 (info_ptr->color_type == PNG_COLOR_TYPE_RGB ||
2127 info_ptr->color_type == PNG_COLOR_TYPE_GRAY))
2128 {
2129 info_ptr->channels++;
2130 /* If adding a true alpha channel not just filler */
2131 if ((png_ptr->transformations & PNG_ADD_ALPHA) != 0)
2132 info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
2133 }
2134 #endif
2135
2136 #if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED) && \
2137 defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
2138 if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
2139 {
2140 if (png_ptr->user_transform_depth != 0)
2141 info_ptr->bit_depth = png_ptr->user_transform_depth;
2142
2143 if (png_ptr->user_transform_channels != 0)
2144 info_ptr->channels = png_ptr->user_transform_channels;
2145 }
2146 #endif
2147
2148 info_ptr->pixel_depth = (png_byte)(info_ptr->channels *
2149 info_ptr->bit_depth);
2150
2151 info_ptr->rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth, info_ptr->width);
2152
2153 /* Adding in 1.5.4: cache the above value in png_struct so that we can later
2154 * check in png_rowbytes that the user buffer won't get overwritten. Note
2155 * that the field is not always set - if png_read_update_info isn't called
2156 * the application has to either not do any transforms or get the calculation
2157 * right itself.
2158 */
2159 png_ptr->info_rowbytes = info_ptr->rowbytes;
2160
2161 #ifndef PNG_READ_EXPAND_SUPPORTED
2162 if (png_ptr != NULL)
2163 return;
2164 #endif
2165 }
2166
2167 #ifdef PNG_READ_PACK_SUPPORTED
2168 /* Unpack pixels of 1, 2, or 4 bits per pixel into 1 byte per pixel,
2169 * without changing the actual values. Thus, if you had a row with
2170 * a bit depth of 1, you would end up with bytes that only contained
2171 * the numbers 0 or 1. If you would rather they contain 0 and 255, use
2172 * png_do_shift() after this.
2173 */
2174 static void
2175 png_do_unpack(png_row_infop row_info, png_bytep row)
2176 {
2177 png_debug(1, "in png_do_unpack");
2178
2179 if (row_info->bit_depth < 8)
2180 {
2181 png_uint_32 i;
2182 png_uint_32 row_width=row_info->width;
2183
2184 switch (row_info->bit_depth)
2185 {
2186 case 1:
2187 {
2188 png_bytep sp = row + (size_t)((row_width - 1) >> 3);
2189 png_bytep dp = row + (size_t)row_width - 1;
2190 png_uint_32 shift = 7U - ((row_width + 7U) & 0x07);
2191 for (i = 0; i < row_width; i++)
2192 {
2193 *dp = (png_byte)((*sp >> shift) & 0x01);
2194
2195 if (shift == 7)
2196 {
2197 shift = 0;
2198 sp--;
2199 }
2200
2201 else
2202 shift++;
2203
2204 dp--;
2205 }
2206 break;
2207 }
2208
2209 case 2:
2210 {
2211
2212 png_bytep sp = row + (size_t)((row_width - 1) >> 2);
2213 png_bytep dp = row + (size_t)row_width - 1;
2214 png_uint_32 shift = ((3U - ((row_width + 3U) & 0x03)) << 1);
2215 for (i = 0; i < row_width; i++)
2216 {
2217 *dp = (png_byte)((*sp >> shift) & 0x03);
2218
2219 if (shift == 6)
2220 {
2221 shift = 0;
2222 sp--;
2223 }
2224
2225 else
2226 shift += 2;
2227
2228 dp--;
2229 }
2230 break;
2231 }
2232
2233 case 4:
2234 {
2235 png_bytep sp = row + (size_t)((row_width - 1) >> 1);
2236 png_bytep dp = row + (size_t)row_width - 1;
2237 png_uint_32 shift = ((1U - ((row_width + 1U) & 0x01)) << 2);
2238 for (i = 0; i < row_width; i++)
2239 {
2240 *dp = (png_byte)((*sp >> shift) & 0x0f);
2241
2242 if (shift == 4)
2243 {
2244 shift = 0;
2245 sp--;
2246 }
2247
2248 else
2249 shift = 4;
2250
2251 dp--;
2252 }
2253 break;
2254 }
2255
2256 default:
2257 break;
2258 }
2259 row_info->bit_depth = 8;
2260 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2261 row_info->rowbytes = row_width * row_info->channels;
2262 }
2263 }
2264 #endif
2265
2266 #ifdef PNG_READ_SHIFT_SUPPORTED
2267 /* Reverse the effects of png_do_shift. This routine merely shifts the
2268 * pixels back to their significant bits values. Thus, if you have
2269 * a row of bit depth 8, but only 5 are significant, this will shift
2270 * the values back to 0 through 31.
2271 */
2272 static void
2273 png_do_unshift(png_row_infop row_info, png_bytep row,
2274 png_const_color_8p sig_bits)
2275 {
2276 int color_type;
2277
2278 png_debug(1, "in png_do_unshift");
2279
2280 /* The palette case has already been handled in the _init routine. */
2281 color_type = row_info->color_type;
2282
2283 if (color_type != PNG_COLOR_TYPE_PALETTE)
2284 {
2285 int shift[4];
2286 int channels = 0;
2287 int bit_depth = row_info->bit_depth;
2288
2289 if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
2290 {
2291 shift[channels++] = bit_depth - sig_bits->red;
2292 shift[channels++] = bit_depth - sig_bits->green;
2293 shift[channels++] = bit_depth - sig_bits->blue;
2294 }
2295
2296 else
2297 {
2298 shift[channels++] = bit_depth - sig_bits->gray;
2299 }
2300
2301 if ((color_type & PNG_COLOR_MASK_ALPHA) != 0)
2302 {
2303 shift[channels++] = bit_depth - sig_bits->alpha;
2304 }
2305
2306 {
2307 int c, have_shift;
2308
2309 for (c = have_shift = 0; c < channels; ++c)
2310 {
2311 /* A shift of more than the bit depth is an error condition but it
2312 * gets ignored here.
2313 */
2314 if (shift[c] <= 0 || shift[c] >= bit_depth)
2315 shift[c] = 0;
2316
2317 else
2318 have_shift = 1;
2319 }
2320
2321 if (have_shift == 0)
2322 return;
2323 }
2324
2325 switch (bit_depth)
2326 {
2327 default:
2328 /* Must be 1bpp gray: should not be here! */
2329 /* NOTREACHED */
2330 break;
2331
2332 case 2:
2333 /* Must be 2bpp gray */
2334 /* assert(channels == 1 && shift[0] == 1) */
2335 {
2336 png_bytep bp = row;
2337 png_bytep bp_end = bp + row_info->rowbytes;
2338
2339 while (bp < bp_end)
2340 {
2341 int b = (*bp >> 1) & 0x55;
2342 *bp++ = (png_byte)b;
2343 }
2344 break;
2345 }
2346
2347 case 4:
2348 /* Must be 4bpp gray */
2349 /* assert(channels == 1) */
2350 {
2351 png_bytep bp = row;
2352 png_bytep bp_end = bp + row_info->rowbytes;
2353 int gray_shift = shift[0];
2354 int mask = 0xf >> gray_shift;
2355
2356 mask |= mask << 4;
2357
2358 while (bp < bp_end)
2359 {
2360 int b = (*bp >> gray_shift) & mask;
2361 *bp++ = (png_byte)b;
2362 }
2363 break;
2364 }
2365
2366 case 8:
2367 /* Single byte components, G, GA, RGB, RGBA */
2368 {
2369 png_bytep bp = row;
2370 png_bytep bp_end = bp + row_info->rowbytes;
2371 int channel = 0;
2372
2373 while (bp < bp_end)
2374 {
2375 int b = *bp >> shift[channel];
2376 if (++channel >= channels)
2377 channel = 0;
2378 *bp++ = (png_byte)b;
2379 }
2380 break;
2381 }
2382
2383 #ifdef PNG_READ_16BIT_SUPPORTED
2384 case 16:
2385 /* Double byte components, G, GA, RGB, RGBA */
2386 {
2387 png_bytep bp = row;
2388 png_bytep bp_end = bp + row_info->rowbytes;
2389 int channel = 0;
2390
2391 while (bp < bp_end)
2392 {
2393 int value = (bp[0] << 8) + bp[1];
2394
2395 value >>= shift[channel];
2396 if (++channel >= channels)
2397 channel = 0;
2398 *bp++ = (png_byte)(value >> 8);
2399 *bp++ = (png_byte)value;
2400 }
2401 break;
2402 }
2403 #endif
2404 }
2405 }
2406 }
2407 #endif
2408
2409 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
2410 /* Scale rows of bit depth 16 down to 8 accurately */
2411 static void
2412 png_do_scale_16_to_8(png_row_infop row_info, png_bytep row)
2413 {
2414 png_debug(1, "in png_do_scale_16_to_8");
2415
2416 if (row_info->bit_depth == 16)
2417 {
2418 png_bytep sp = row; /* source */
2419 png_bytep dp = row; /* destination */
2420 png_bytep ep = sp + row_info->rowbytes; /* end+1 */
2421
2422 while (sp < ep)
2423 {
2424 /* The input is an array of 16-bit components, these must be scaled to
2425 * 8 bits each. For a 16-bit value V the required value (from the PNG
2426 * specification) is:
2427 *
2428 * (V * 255) / 65535
2429 *
2430 * This reduces to round(V / 257), or floor((V + 128.5)/257)
2431 *
2432 * Represent V as the two byte value vhi.vlo. Make a guess that the
2433 * result is the top byte of V, vhi, then the correction to this value
2434 * is:
2435 *
2436 * error = floor(((V-vhi.vhi) + 128.5) / 257)
2437 * = floor(((vlo-vhi) + 128.5) / 257)
2438 *
2439 * This can be approximated using integer arithmetic (and a signed
2440 * shift):
2441 *
2442 * error = (vlo-vhi+128) >> 8;
2443 *
2444 * The approximate differs from the exact answer only when (vlo-vhi) is
2445 * 128; it then gives a correction of +1 when the exact correction is
2446 * 0. This gives 128 errors. The exact answer (correct for all 16-bit
2447 * input values) is:
2448 *
2449 * error = (vlo-vhi+128)*65535 >> 24;
2450 *
2451 * An alternative arithmetic calculation which also gives no errors is:
2452 *
2453 * (V * 255 + 32895) >> 16
2454 */
2455
2456 png_int_32 tmp = *sp++; /* must be signed! */
2457 tmp += (((int)*sp++ - tmp + 128) * 65535) >> 24;
2458 *dp++ = (png_byte)tmp;
2459 }
2460
2461 row_info->bit_depth = 8;
2462 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2463 row_info->rowbytes = row_info->width * row_info->channels;
2464 }
2465 }
2466 #endif
2467
2468 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
2469 static void
2470 /* Simply discard the low byte. This was the default behavior prior
2471 * to libpng-1.5.4.
2472 */
2473 png_do_chop(png_row_infop row_info, png_bytep row)
2474 {
2475 png_debug(1, "in png_do_chop");
2476
2477 if (row_info->bit_depth == 16)
2478 {
2479 png_bytep sp = row; /* source */
2480 png_bytep dp = row; /* destination */
2481 png_bytep ep = sp + row_info->rowbytes; /* end+1 */
2482
2483 while (sp < ep)
2484 {
2485 *dp++ = *sp;
2486 sp += 2; /* skip low byte */
2487 }
2488
2489 row_info->bit_depth = 8;
2490 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
2491 row_info->rowbytes = row_info->width * row_info->channels;
2492 }
2493 }
2494 #endif
2495
2496 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
2497 static void
2498 png_do_read_swap_alpha(png_row_infop row_info, png_bytep row)
2499 {
2500 png_uint_32 row_width = row_info->width;
2501
2502 png_debug(1, "in png_do_read_swap_alpha");
2503
2504 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
2505 {
2506 /* This converts from RGBA to ARGB */
2507 if (row_info->bit_depth == 8)
2508 {
2509 png_bytep sp = row + row_info->rowbytes;
2510 png_bytep dp = sp;
2511 png_byte save;
2512 png_uint_32 i;
2513
2514 for (i = 0; i < row_width; i++)
2515 {
2516 save = *(--sp);
2517 *(--dp) = *(--sp);
2518 *(--dp) = *(--sp);
2519 *(--dp) = *(--sp);
2520 *(--dp) = save;
2521 }
2522 }
2523
2524 #ifdef PNG_READ_16BIT_SUPPORTED
2525 /* This converts from RRGGBBAA to AARRGGBB */
2526 else
2527 {
2528 png_bytep sp = row + row_info->rowbytes;
2529 png_bytep dp = sp;
2530 png_byte save[2];
2531 png_uint_32 i;
2532
2533 for (i = 0; i < row_width; i++)
2534 {
2535 save[0] = *(--sp);
2536 save[1] = *(--sp);
2537 *(--dp) = *(--sp);
2538 *(--dp) = *(--sp);
2539 *(--dp) = *(--sp);
2540 *(--dp) = *(--sp);
2541 *(--dp) = *(--sp);
2542 *(--dp) = *(--sp);
2543 *(--dp) = save[0];
2544 *(--dp) = save[1];
2545 }
2546 }
2547 #endif
2548 }
2549
2550 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2551 {
2552 /* This converts from GA to AG */
2553 if (row_info->bit_depth == 8)
2554 {
2555 png_bytep sp = row + row_info->rowbytes;
2556 png_bytep dp = sp;
2557 png_byte save;
2558 png_uint_32 i;
2559
2560 for (i = 0; i < row_width; i++)
2561 {
2562 save = *(--sp);
2563 *(--dp) = *(--sp);
2564 *(--dp) = save;
2565 }
2566 }
2567
2568 #ifdef PNG_READ_16BIT_SUPPORTED
2569 /* This converts from GGAA to AAGG */
2570 else
2571 {
2572 png_bytep sp = row + row_info->rowbytes;
2573 png_bytep dp = sp;
2574 png_byte save[2];
2575 png_uint_32 i;
2576
2577 for (i = 0; i < row_width; i++)
2578 {
2579 save[0] = *(--sp);
2580 save[1] = *(--sp);
2581 *(--dp) = *(--sp);
2582 *(--dp) = *(--sp);
2583 *(--dp) = save[0];
2584 *(--dp) = save[1];
2585 }
2586 }
2587 #endif
2588 }
2589 }
2590 #endif
2591
2592 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
2593 static void
2594 png_do_read_invert_alpha(png_row_infop row_info, png_bytep row)
2595 {
2596 png_uint_32 row_width;
2597 png_debug(1, "in png_do_read_invert_alpha");
2598
2599 row_width = row_info->width;
2600 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
2601 {
2602 if (row_info->bit_depth == 8)
2603 {
2604 /* This inverts the alpha channel in RGBA */
2605 png_bytep sp = row + row_info->rowbytes;
2606 png_bytep dp = sp;
2607 png_uint_32 i;
2608
2609 for (i = 0; i < row_width; i++)
2610 {
2611 *(--dp) = (png_byte)(255 - *(--sp));
2612
2613 /* This does nothing:
2614 *(--dp) = *(--sp);
2615 *(--dp) = *(--sp);
2616 *(--dp) = *(--sp);
2617 We can replace it with:
2618 */
2619 sp-=3;
2620 dp=sp;
2621 }
2622 }
2623
2624 #ifdef PNG_READ_16BIT_SUPPORTED
2625 /* This inverts the alpha channel in RRGGBBAA */
2626 else
2627 {
2628 png_bytep sp = row + row_info->rowbytes;
2629 png_bytep dp = sp;
2630 png_uint_32 i;
2631
2632 for (i = 0; i < row_width; i++)
2633 {
2634 *(--dp) = (png_byte)(255 - *(--sp));
2635 *(--dp) = (png_byte)(255 - *(--sp));
2636
2637 /* This does nothing:
2638 *(--dp) = *(--sp);
2639 *(--dp) = *(--sp);
2640 *(--dp) = *(--sp);
2641 *(--dp) = *(--sp);
2642 *(--dp) = *(--sp);
2643 *(--dp) = *(--sp);
2644 We can replace it with:
2645 */
2646 sp-=6;
2647 dp=sp;
2648 }
2649 }
2650 #endif
2651 }
2652 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2653 {
2654 if (row_info->bit_depth == 8)
2655 {
2656 /* This inverts the alpha channel in GA */
2657 png_bytep sp = row + row_info->rowbytes;
2658 png_bytep dp = sp;
2659 png_uint_32 i;
2660
2661 for (i = 0; i < row_width; i++)
2662 {
2663 *(--dp) = (png_byte)(255 - *(--sp));
2664 *(--dp) = *(--sp);
2665 }
2666 }
2667
2668 #ifdef PNG_READ_16BIT_SUPPORTED
2669 else
2670 {
2671 /* This inverts the alpha channel in GGAA */
2672 png_bytep sp = row + row_info->rowbytes;
2673 png_bytep dp = sp;
2674 png_uint_32 i;
2675
2676 for (i = 0; i < row_width; i++)
2677 {
2678 *(--dp) = (png_byte)(255 - *(--sp));
2679 *(--dp) = (png_byte)(255 - *(--sp));
2680 /*
2681 *(--dp) = *(--sp);
2682 *(--dp) = *(--sp);
2683 */
2684 sp-=2;
2685 dp=sp;
2686 }
2687 }
2688 #endif
2689 }
2690 }
2691 #endif
2692
2693 #ifdef PNG_READ_FILLER_SUPPORTED
2694 /* Add filler channel if we have RGB color */
2695 static void
2696 png_do_read_filler(png_row_infop row_info, png_bytep row,
2697 png_uint_32 filler, png_uint_32 flags)
2698 {
2699 png_uint_32 i;
2700 png_uint_32 row_width = row_info->width;
2701
2702 #ifdef PNG_READ_16BIT_SUPPORTED
2703 png_byte hi_filler = (png_byte)(filler>>8);
2704 #endif
2705 png_byte lo_filler = (png_byte)filler;
2706
2707 png_debug(1, "in png_do_read_filler");
2708
2709 if (
2710 row_info->color_type == PNG_COLOR_TYPE_GRAY)
2711 {
2712 if (row_info->bit_depth == 8)
2713 {
2714 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2715 {
2716 /* This changes the data from G to GX */
2717 png_bytep sp = row + (size_t)row_width;
2718 png_bytep dp = sp + (size_t)row_width;
2719 for (i = 1; i < row_width; i++)
2720 {
2721 *(--dp) = lo_filler;
2722 *(--dp) = *(--sp);
2723 }
2724 *(--dp) = lo_filler;
2725 row_info->channels = 2;
2726 row_info->pixel_depth = 16;
2727 row_info->rowbytes = row_width * 2;
2728 }
2729
2730 else
2731 {
2732 /* This changes the data from G to XG */
2733 png_bytep sp = row + (size_t)row_width;
2734 png_bytep dp = sp + (size_t)row_width;
2735 for (i = 0; i < row_width; i++)
2736 {
2737 *(--dp) = *(--sp);
2738 *(--dp) = lo_filler;
2739 }
2740 row_info->channels = 2;
2741 row_info->pixel_depth = 16;
2742 row_info->rowbytes = row_width * 2;
2743 }
2744 }
2745
2746 #ifdef PNG_READ_16BIT_SUPPORTED
2747 else if (row_info->bit_depth == 16)
2748 {
2749 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2750 {
2751 /* This changes the data from GG to GGXX */
2752 png_bytep sp = row + (size_t)row_width * 2;
2753 png_bytep dp = sp + (size_t)row_width * 2;
2754 for (i = 1; i < row_width; i++)
2755 {
2756 *(--dp) = lo_filler;
2757 *(--dp) = hi_filler;
2758 *(--dp) = *(--sp);
2759 *(--dp) = *(--sp);
2760 }
2761 *(--dp) = lo_filler;
2762 *(--dp) = hi_filler;
2763 row_info->channels = 2;
2764 row_info->pixel_depth = 32;
2765 row_info->rowbytes = row_width * 4;
2766 }
2767
2768 else
2769 {
2770 /* This changes the data from GG to XXGG */
2771 png_bytep sp = row + (size_t)row_width * 2;
2772 png_bytep dp = sp + (size_t)row_width * 2;
2773 for (i = 0; i < row_width; i++)
2774 {
2775 *(--dp) = *(--sp);
2776 *(--dp) = *(--sp);
2777 *(--dp) = lo_filler;
2778 *(--dp) = hi_filler;
2779 }
2780 row_info->channels = 2;
2781 row_info->pixel_depth = 32;
2782 row_info->rowbytes = row_width * 4;
2783 }
2784 }
2785 #endif
2786 } /* COLOR_TYPE == GRAY */
2787 else if (row_info->color_type == PNG_COLOR_TYPE_RGB)
2788 {
2789 if (row_info->bit_depth == 8)
2790 {
2791 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2792 {
2793 /* This changes the data from RGB to RGBX */
2794 png_bytep sp = row + (size_t)row_width * 3;
2795 png_bytep dp = sp + (size_t)row_width;
2796 for (i = 1; i < row_width; i++)
2797 {
2798 *(--dp) = lo_filler;
2799 *(--dp) = *(--sp);
2800 *(--dp) = *(--sp);
2801 *(--dp) = *(--sp);
2802 }
2803 *(--dp) = lo_filler;
2804 row_info->channels = 4;
2805 row_info->pixel_depth = 32;
2806 row_info->rowbytes = row_width * 4;
2807 }
2808
2809 else
2810 {
2811 /* This changes the data from RGB to XRGB */
2812 png_bytep sp = row + (size_t)row_width * 3;
2813 png_bytep dp = sp + (size_t)row_width;
2814 for (i = 0; i < row_width; i++)
2815 {
2816 *(--dp) = *(--sp);
2817 *(--dp) = *(--sp);
2818 *(--dp) = *(--sp);
2819 *(--dp) = lo_filler;
2820 }
2821 row_info->channels = 4;
2822 row_info->pixel_depth = 32;
2823 row_info->rowbytes = row_width * 4;
2824 }
2825 }
2826
2827 #ifdef PNG_READ_16BIT_SUPPORTED
2828 else if (row_info->bit_depth == 16)
2829 {
2830 if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
2831 {
2832 /* This changes the data from RRGGBB to RRGGBBXX */
2833 png_bytep sp = row + (size_t)row_width * 6;
2834 png_bytep dp = sp + (size_t)row_width * 2;
2835 for (i = 1; i < row_width; i++)
2836 {
2837 *(--dp) = lo_filler;
2838 *(--dp) = hi_filler;
2839 *(--dp) = *(--sp);
2840 *(--dp) = *(--sp);
2841 *(--dp) = *(--sp);
2842 *(--dp) = *(--sp);
2843 *(--dp) = *(--sp);
2844 *(--dp) = *(--sp);
2845 }
2846 *(--dp) = lo_filler;
2847 *(--dp) = hi_filler;
2848 row_info->channels = 4;
2849 row_info->pixel_depth = 64;
2850 row_info->rowbytes = row_width * 8;
2851 }
2852
2853 else
2854 {
2855 /* This changes the data from RRGGBB to XXRRGGBB */
2856 png_bytep sp = row + (size_t)row_width * 6;
2857 png_bytep dp = sp + (size_t)row_width * 2;
2858 for (i = 0; i < row_width; i++)
2859 {
2860 *(--dp) = *(--sp);
2861 *(--dp) = *(--sp);
2862 *(--dp) = *(--sp);
2863 *(--dp) = *(--sp);
2864 *(--dp) = *(--sp);
2865 *(--dp) = *(--sp);
2866 *(--dp) = lo_filler;
2867 *(--dp) = hi_filler;
2868 }
2869
2870 row_info->channels = 4;
2871 row_info->pixel_depth = 64;
2872 row_info->rowbytes = row_width * 8;
2873 }
2874 }
2875 #endif
2876 } /* COLOR_TYPE == RGB */
2877 }
2878 #endif
2879
2880 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
2881 /* Expand grayscale files to RGB, with or without alpha */
2882 static void
2883 png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
2884 {
2885 png_uint_32 i;
2886 png_uint_32 row_width = row_info->width;
2887
2888 png_debug(1, "in png_do_gray_to_rgb");
2889
2890 if (row_info->bit_depth >= 8 &&
2891 (row_info->color_type & PNG_COLOR_MASK_COLOR) == 0)
2892 {
2893 if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
2894 {
2895 if (row_info->bit_depth == 8)
2896 {
2897 /* This changes G to RGB */
2898 png_bytep sp = row + (size_t)row_width - 1;
2899 png_bytep dp = sp + (size_t)row_width * 2;
2900 for (i = 0; i < row_width; i++)
2901 {
2902 *(dp--) = *sp;
2903 *(dp--) = *sp;
2904 *(dp--) = *(sp--);
2905 }
2906 }
2907
2908 else
2909 {
2910 /* This changes GG to RRGGBB */
2911 png_bytep sp = row + (size_t)row_width * 2 - 1;
2912 png_bytep dp = sp + (size_t)row_width * 4;
2913 for (i = 0; i < row_width; i++)
2914 {
2915 *(dp--) = *sp;
2916 *(dp--) = *(sp - 1);
2917 *(dp--) = *sp;
2918 *(dp--) = *(sp - 1);
2919 *(dp--) = *(sp--);
2920 *(dp--) = *(sp--);
2921 }
2922 }
2923 }
2924
2925 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
2926 {
2927 if (row_info->bit_depth == 8)
2928 {
2929 /* This changes GA to RGBA */
2930 png_bytep sp = row + (size_t)row_width * 2 - 1;
2931 png_bytep dp = sp + (size_t)row_width * 2;
2932 for (i = 0; i < row_width; i++)
2933 {
2934 *(dp--) = *(sp--);
2935 *(dp--) = *sp;
2936 *(dp--) = *sp;
2937 *(dp--) = *(sp--);
2938 }
2939 }
2940
2941 else
2942 {
2943 /* This changes GGAA to RRGGBBAA */
2944 png_bytep sp = row + (size_t)row_width * 4 - 1;
2945 png_bytep dp = sp + (size_t)row_width * 4;
2946 for (i = 0; i < row_width; i++)
2947 {
2948 *(dp--) = *(sp--);
2949 *(dp--) = *(sp--);
2950 *(dp--) = *sp;
2951 *(dp--) = *(sp - 1);
2952 *(dp--) = *sp;
2953 *(dp--) = *(sp - 1);
2954 *(dp--) = *(sp--);
2955 *(dp--) = *(sp--);
2956 }
2957 }
2958 }
2959 row_info->channels = (png_byte)(row_info->channels + 2);
2960 row_info->color_type |= PNG_COLOR_MASK_COLOR;
2961 row_info->pixel_depth = (png_byte)(row_info->channels *
2962 row_info->bit_depth);
2963 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
2964 }
2965 }
2966 #endif
2967
2968 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2969 /* Reduce RGB files to grayscale, with or without alpha
2970 * using the equation given in Poynton's ColorFAQ of 1998-01-04 at
2971 * <http://www.inforamp.net/~poynton/> (THIS LINK IS DEAD June 2008 but
2972 * versions dated 1998 through November 2002 have been archived at
2973 * https://web.archive.org/web/20000816232553/www.inforamp.net/
2974 * ~poynton/notes/colour_and_gamma/ColorFAQ.txt )
2975 * Charles Poynton poynton at poynton.com
2976 *
2977 * Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
2978 *
2979 * which can be expressed with integers as
2980 *
2981 * Y = (6969 * R + 23434 * G + 2365 * B)/32768
2982 *
2983 * Poynton's current link (as of January 2003 through July 2011):
2984 * <http://www.poynton.com/notes/colour_and_gamma/>
2985 * has changed the numbers slightly:
2986 *
2987 * Y = 0.2126*R + 0.7152*G + 0.0722*B
2988 *
2989 * which can be expressed with integers as
2990 *
2991 * Y = (6966 * R + 23436 * G + 2366 * B)/32768
2992 *
2993 * Historically, however, libpng uses numbers derived from the ITU-R Rec 709
2994 * end point chromaticities and the D65 white point. Depending on the
2995 * precision used for the D65 white point this produces a variety of different
2996 * numbers, however if the four decimal place value used in ITU-R Rec 709 is
2997 * used (0.3127,0.3290) the Y calculation would be:
2998 *
2999 * Y = (6968 * R + 23435 * G + 2366 * B)/32768
3000 *
3001 * While this is correct the rounding results in an overflow for white, because
3002 * the sum of the rounded coefficients is 32769, not 32768. Consequently
3003 * libpng uses, instead, the closest non-overflowing approximation:
3004 *
3005 * Y = (6968 * R + 23434 * G + 2366 * B)/32768
3006 *
3007 * Starting with libpng-1.5.5, if the image being converted has a cHRM chunk
3008 * (including an sRGB chunk) then the chromaticities are used to calculate the
3009 * coefficients. See the chunk handling in pngrutil.c for more information.
3010 *
3011 * In all cases the calculation is to be done in a linear colorspace. If no
3012 * gamma information is available to correct the encoding of the original RGB
3013 * values this results in an implicit assumption that the original PNG RGB
3014 * values were linear.
3015 *
3016 * Other integer coefficients can be used via png_set_rgb_to_gray(). Because
3017 * the API takes just red and green coefficients the blue coefficient is
3018 * calculated to make the sum 32768. This will result in different rounding
3019 * to that used above.
3020 */
3021 static int
3022 png_do_rgb_to_gray(png_structrp png_ptr, png_row_infop row_info, png_bytep row)
3023 {
3024 int rgb_error = 0;
3025
3026 png_debug(1, "in png_do_rgb_to_gray");
3027
3028 if ((row_info->color_type & PNG_COLOR_MASK_PALETTE) == 0 &&
3029 (row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
3030 {
3031 png_uint_32 rc = png_ptr->rgb_to_gray_red_coeff;
3032 png_uint_32 gc = png_ptr->rgb_to_gray_green_coeff;
3033 png_uint_32 bc = 32768 - rc - gc;
3034 png_uint_32 row_width = row_info->width;
3035 int have_alpha = (row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0;
3036
3037 if (row_info->bit_depth == 8)
3038 {
3039 #ifdef PNG_READ_GAMMA_SUPPORTED
3040 /* Notice that gamma to/from 1 are not necessarily inverses (if
3041 * there is an overall gamma correction). Prior to 1.5.5 this code
3042 * checked the linearized values for equality; this doesn't match
3043 * the documentation, the original values must be checked.
3044 */
3045 if (png_ptr->gamma_from_1 != NULL && png_ptr->gamma_to_1 != NULL)
3046 {
3047 png_bytep sp = row;
3048 png_bytep dp = row;
3049 png_uint_32 i;
3050
3051 for (i = 0; i < row_width; i++)
3052 {
3053 png_byte red = *(sp++);
3054 png_byte green = *(sp++);
3055 png_byte blue = *(sp++);
3056
3057 if (red != green || red != blue)
3058 {
3059 red = png_ptr->gamma_to_1[red];
3060 green = png_ptr->gamma_to_1[green];
3061 blue = png_ptr->gamma_to_1[blue];
3062
3063 rgb_error |= 1;
3064 *(dp++) = png_ptr->gamma_from_1[
3065 (rc*red + gc*green + bc*blue + 16384)>>15];
3066 }
3067
3068 else
3069 {
3070 /* If there is no overall correction the table will not be
3071 * set.
3072 */
3073 if (png_ptr->gamma_table != NULL)
3074 red = png_ptr->gamma_table[red];
3075
3076 *(dp++) = red;
3077 }
3078
3079 if (have_alpha != 0)
3080 *(dp++) = *(sp++);
3081 }
3082 }
3083 else
3084 #endif
3085 {
3086 png_bytep sp = row;
3087 png_bytep dp = row;
3088 png_uint_32 i;
3089
3090 for (i = 0; i < row_width; i++)
3091 {
3092 png_byte red = *(sp++);
3093 png_byte green = *(sp++);
3094 png_byte blue = *(sp++);
3095
3096 if (red != green || red != blue)
3097 {
3098 rgb_error |= 1;
3099 /* NOTE: this is the historical approach which simply
3100 * truncates the results.
3101 */
3102 *(dp++) = (png_byte)((rc*red + gc*green + bc*blue)>>15);
3103 }
3104
3105 else
3106 *(dp++) = red;
3107
3108 if (have_alpha != 0)
3109 *(dp++) = *(sp++);
3110 }
3111 }
3112 }
3113
3114 else /* RGB bit_depth == 16 */
3115 {
3116 #ifdef PNG_READ_GAMMA_SUPPORTED
3117 if (png_ptr->gamma_16_to_1 != NULL && png_ptr->gamma_16_from_1 != NULL)
3118 {
3119 png_bytep sp = row;
3120 png_bytep dp = row;
3121 png_uint_32 i;
3122
3123 for (i = 0; i < row_width; i++)
3124 {
3125 png_uint_16 red, green, blue, w;
3126 png_byte hi,lo;
3127
3128 hi=*(sp)++; lo=*(sp)++; red = (png_uint_16)((hi << 8) | (lo));
3129 hi=*(sp)++; lo=*(sp)++; green = (png_uint_16)((hi << 8) | (lo));
3130 hi=*(sp)++; lo=*(sp)++; blue = (png_uint_16)((hi << 8) | (lo));
3131
3132 if (red == green && red == blue)
3133 {
3134 if (png_ptr->gamma_16_table != NULL)
3135 w = png_ptr->gamma_16_table[(red & 0xff)
3136 >> png_ptr->gamma_shift][red >> 8];
3137
3138 else
3139 w = red;
3140 }
3141
3142 else
3143 {
3144 png_uint_16 red_1 = png_ptr->gamma_16_to_1[(red & 0xff)
3145 >> png_ptr->gamma_shift][red>>8];
3146 png_uint_16 green_1 =
3147 png_ptr->gamma_16_to_1[(green & 0xff) >>
3148 png_ptr->gamma_shift][green>>8];
3149 png_uint_16 blue_1 = png_ptr->gamma_16_to_1[(blue & 0xff)
3150 >> png_ptr->gamma_shift][blue>>8];
3151 png_uint_16 gray16 = (png_uint_16)((rc*red_1 + gc*green_1
3152 + bc*blue_1 + 16384)>>15);
3153 w = png_ptr->gamma_16_from_1[(gray16 & 0xff) >>
3154 png_ptr->gamma_shift][gray16 >> 8];
3155 rgb_error |= 1;
3156 }
3157
3158 *(dp++) = (png_byte)((w>>8) & 0xff);
3159 *(dp++) = (png_byte)(w & 0xff);
3160
3161 if (have_alpha != 0)
3162 {
3163 *(dp++) = *(sp++);
3164 *(dp++) = *(sp++);
3165 }
3166 }
3167 }
3168 else
3169 #endif
3170 {
3171 png_bytep sp = row;
3172 png_bytep dp = row;
3173 png_uint_32 i;
3174
3175 for (i = 0; i < row_width; i++)
3176 {
3177 png_uint_16 red, green, blue, gray16;
3178 png_byte hi,lo;
3179
3180 hi=*(sp)++; lo=*(sp)++; red = (png_uint_16)((hi << 8) | (lo));
3181 hi=*(sp)++; lo=*(sp)++; green = (png_uint_16)((hi << 8) | (lo));
3182 hi=*(sp)++; lo=*(sp)++; blue = (png_uint_16)((hi << 8) | (lo));
3183
3184 if (red != green || red != blue)
3185 rgb_error |= 1;
3186
3187 /* From 1.5.5 in the 16-bit case do the accurate conversion even
3188 * in the 'fast' case - this is because this is where the code
3189 * ends up when handling linear 16-bit data.
3190 */
3191 gray16 = (png_uint_16)((rc*red + gc*green + bc*blue + 16384) >>
3192 15);
3193 *(dp++) = (png_byte)((gray16 >> 8) & 0xff);
3194 *(dp++) = (png_byte)(gray16 & 0xff);
3195
3196 if (have_alpha != 0)
3197 {
3198 *(dp++) = *(sp++);
3199 *(dp++) = *(sp++);
3200 }
3201 }
3202 }
3203 }
3204
3205 row_info->channels = (png_byte)(row_info->channels - 2);
3206 row_info->color_type = (png_byte)(row_info->color_type &
3207 ~PNG_COLOR_MASK_COLOR);
3208 row_info->pixel_depth = (png_byte)(row_info->channels *
3209 row_info->bit_depth);
3210 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
3211 }
3212 return rgb_error;
3213 }
3214 #endif
3215
3216 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
3217 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
3218 /* Replace any alpha or transparency with the supplied background color.
3219 * "background" is already in the screen gamma, while "background_1" is
3220 * at a gamma of 1.0. Paletted files have already been taken care of.
3221 */
3222 static void
3223 png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
3224 {
3225 #ifdef PNG_READ_GAMMA_SUPPORTED
3226 png_const_bytep gamma_table = png_ptr->gamma_table;
3227 png_const_bytep gamma_from_1 = png_ptr->gamma_from_1;
3228 png_const_bytep gamma_to_1 = png_ptr->gamma_to_1;
3229 png_const_uint_16pp gamma_16 = png_ptr->gamma_16_table;
3230 png_const_uint_16pp gamma_16_from_1 = png_ptr->gamma_16_from_1;
3231 png_const_uint_16pp gamma_16_to_1 = png_ptr->gamma_16_to_1;
3232 int gamma_shift = png_ptr->gamma_shift;
3233 int optimize = (png_ptr->flags & PNG_FLAG_OPTIMIZE_ALPHA) != 0;
3234 #endif
3235
3236 png_bytep sp;
3237 png_uint_32 i;
3238 png_uint_32 row_width = row_info->width;
3239 int shift;
3240
3241 png_debug(1, "in png_do_compose");
3242
3243 switch (row_info->color_type)
3244 {
3245 case PNG_COLOR_TYPE_GRAY:
3246 {
3247 switch (row_info->bit_depth)
3248 {
3249 case 1:
3250 {
3251 sp = row;
3252 shift = 7;
3253 for (i = 0; i < row_width; i++)
3254 {
3255 if ((png_uint_16)((*sp >> shift) & 0x01)
3256 == png_ptr->trans_color.gray)
3257 {
3258 unsigned int tmp = *sp & (0x7f7f >> (7 - shift));
3259 tmp |=
3260 (unsigned int)(png_ptr->background.gray << shift);
3261 *sp = (png_byte)(tmp & 0xff);
3262 }
3263
3264 if (shift == 0)
3265 {
3266 shift = 7;
3267 sp++;
3268 }
3269
3270 else
3271 shift--;
3272 }
3273 break;
3274 }
3275
3276 case 2:
3277 {
3278 #ifdef PNG_READ_GAMMA_SUPPORTED
3279 if (gamma_table != NULL)
3280 {
3281 sp = row;
3282 shift = 6;
3283 for (i = 0; i < row_width; i++)
3284 {
3285 if ((png_uint_16)((*sp >> shift) & 0x03)
3286 == png_ptr->trans_color.gray)
3287 {
3288 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3289 tmp |=
3290 (unsigned int)png_ptr->background.gray << shift;
3291 *sp = (png_byte)(tmp & 0xff);
3292 }
3293
3294 else
3295 {
3296 unsigned int p = (*sp >> shift) & 0x03;
3297 unsigned int g = (gamma_table [p | (p << 2) |
3298 (p << 4) | (p << 6)] >> 6) & 0x03;
3299 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3300 tmp |= (unsigned int)(g << shift);
3301 *sp = (png_byte)(tmp & 0xff);
3302 }
3303
3304 if (shift == 0)
3305 {
3306 shift = 6;
3307 sp++;
3308 }
3309
3310 else
3311 shift -= 2;
3312 }
3313 }
3314
3315 else
3316 #endif
3317 {
3318 sp = row;
3319 shift = 6;
3320 for (i = 0; i < row_width; i++)
3321 {
3322 if ((png_uint_16)((*sp >> shift) & 0x03)
3323 == png_ptr->trans_color.gray)
3324 {
3325 unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
3326 tmp |=
3327 (unsigned int)png_ptr->background.gray << shift;
3328 *sp = (png_byte)(tmp & 0xff);
3329 }
3330
3331 if (shift == 0)
3332 {
3333 shift = 6;
3334 sp++;
3335 }
3336
3337 else
3338 shift -= 2;
3339 }
3340 }
3341 break;
3342 }
3343
3344 case 4:
3345 {
3346 #ifdef PNG_READ_GAMMA_SUPPORTED
3347 if (gamma_table != NULL)
3348 {
3349 sp = row;
3350 shift = 4;
3351 for (i = 0; i < row_width; i++)
3352 {
3353 if ((png_uint_16)((*sp >> shift) & 0x0f)
3354 == png_ptr->trans_color.gray)
3355 {
3356 unsigned int tmp = *sp & (0x0f0f >> (4 - shift));
3357 tmp |=
3358 (unsigned int)(png_ptr->background.gray << shift);
3359 *sp = (png_byte)(tmp & 0xff);
3360 }
3361
3362 else
3363 {
3364 unsigned int p = (*sp >> shift) & 0x0f;
3365 unsigned int g = (gamma_table[p | (p << 4)] >> 4) &
3366 0x0f;
3367 unsigned int tmp = *sp & (0x0f0f >> (4 - shift));
3368 tmp |= (unsigned int)(g << shift);
3369 *sp = (png_byte)(tmp & 0xff);
3370 }
3371
3372 if (shift == 0)
3373 {
3374 shift = 4;
3375 sp++;
3376 }
3377
3378 else
3379 shift -= 4;
3380 }
3381 }
3382
3383 else
3384 #endif
3385 {
3386 sp = row;
3387 shift = 4;
3388 for (i = 0; i < row_width; i++)
3389 {
3390 if ((png_uint_16)((*sp >> shift) & 0x0f)
3391 == png_ptr->trans_color.gray)
3392 {
3393 unsigned int tmp = *sp & (0x0f0f >> (4 - shift));
3394 tmp |=
3395 (unsigned int)(png_ptr->background.gray << shift);
3396 *sp = (png_byte)(tmp & 0xff);
3397 }
3398
3399 if (shift == 0)
3400 {
3401 shift = 4;
3402 sp++;
3403 }
3404
3405 else
3406 shift -= 4;
3407 }
3408 }
3409 break;
3410 }
3411
3412 case 8:
3413 {
3414 #ifdef PNG_READ_GAMMA_SUPPORTED
3415 if (gamma_table != NULL)
3416 {
3417 sp = row;
3418 for (i = 0; i < row_width; i++, sp++)
3419 {
3420 if (*sp == png_ptr->trans_color.gray)
3421 *sp = (png_byte)png_ptr->background.gray;
3422
3423 else
3424 *sp = gamma_table[*sp];
3425 }
3426 }
3427 else
3428 #endif
3429 {
3430 sp = row;
3431 for (i = 0; i < row_width; i++, sp++)
3432 {
3433 if (*sp == png_ptr->trans_color.gray)
3434 *sp = (png_byte)png_ptr->background.gray;
3435 }
3436 }
3437 break;
3438 }
3439
3440 case 16:
3441 {
3442 #ifdef PNG_READ_GAMMA_SUPPORTED
3443 if (gamma_16 != NULL)
3444 {
3445 sp = row;
3446 for (i = 0; i < row_width; i++, sp += 2)
3447 {
3448 png_uint_16 v;
3449
3450 v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3451
3452 if (v == png_ptr->trans_color.gray)
3453 {
3454 /* Background is already in screen gamma */
3455 *sp = (png_byte)((png_ptr->background.gray >> 8)
3456 & 0xff);
3457 *(sp + 1) = (png_byte)(png_ptr->background.gray
3458 & 0xff);
3459 }
3460
3461 else
3462 {
3463 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3464 *sp = (png_byte)((v >> 8) & 0xff);
3465 *(sp + 1) = (png_byte)(v & 0xff);
3466 }
3467 }
3468 }
3469 else
3470 #endif
3471 {
3472 sp = row;
3473 for (i = 0; i < row_width; i++, sp += 2)
3474 {
3475 png_uint_16 v;
3476
3477 v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3478
3479 if (v == png_ptr->trans_color.gray)
3480 {
3481 *sp = (png_byte)((png_ptr->background.gray >> 8)
3482 & 0xff);
3483 *(sp + 1) = (png_byte)(png_ptr->background.gray
3484 & 0xff);
3485 }
3486 }
3487 }
3488 break;
3489 }
3490
3491 default:
3492 break;
3493 }
3494 break;
3495 }
3496
3497 case PNG_COLOR_TYPE_RGB:
3498 {
3499 if (row_info->bit_depth == 8)
3500 {
3501 #ifdef PNG_READ_GAMMA_SUPPORTED
3502 if (gamma_table != NULL)
3503 {
3504 sp = row;
3505 for (i = 0; i < row_width; i++, sp += 3)
3506 {
3507 if (*sp == png_ptr->trans_color.red &&
3508 *(sp + 1) == png_ptr->trans_color.green &&
3509 *(sp + 2) == png_ptr->trans_color.blue)
3510 {
3511 *sp = (png_byte)png_ptr->background.red;
3512 *(sp + 1) = (png_byte)png_ptr->background.green;
3513 *(sp + 2) = (png_byte)png_ptr->background.blue;
3514 }
3515
3516 else
3517 {
3518 *sp = gamma_table[*sp];
3519 *(sp + 1) = gamma_table[*(sp + 1)];
3520 *(sp + 2) = gamma_table[*(sp + 2)];
3521 }
3522 }
3523 }
3524 else
3525 #endif
3526 {
3527 sp = row;
3528 for (i = 0; i < row_width; i++, sp += 3)
3529 {
3530 if (*sp == png_ptr->trans_color.red &&
3531 *(sp + 1) == png_ptr->trans_color.green &&
3532 *(sp + 2) == png_ptr->trans_color.blue)
3533 {
3534 *sp = (png_byte)png_ptr->background.red;
3535 *(sp + 1) = (png_byte)png_ptr->background.green;
3536 *(sp + 2) = (png_byte)png_ptr->background.blue;
3537 }
3538 }
3539 }
3540 }
3541 else /* if (row_info->bit_depth == 16) */
3542 {
3543 #ifdef PNG_READ_GAMMA_SUPPORTED
3544 if (gamma_16 != NULL)
3545 {
3546 sp = row;
3547 for (i = 0; i < row_width; i++, sp += 6)
3548 {
3549 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3550
3551 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
3552 + *(sp + 3));
3553
3554 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
3555 + *(sp + 5));
3556
3557 if (r == png_ptr->trans_color.red &&
3558 g == png_ptr->trans_color.green &&
3559 b == png_ptr->trans_color.blue)
3560 {
3561 /* Background is already in screen gamma */
3562 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3563 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3564 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3565 & 0xff);
3566 *(sp + 3) = (png_byte)(png_ptr->background.green
3567 & 0xff);
3568 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3569 & 0xff);
3570 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3571 }
3572
3573 else
3574 {
3575 png_uint_16 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3576 *sp = (png_byte)((v >> 8) & 0xff);
3577 *(sp + 1) = (png_byte)(v & 0xff);
3578
3579 v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)];
3580 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
3581 *(sp + 3) = (png_byte)(v & 0xff);
3582
3583 v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)];
3584 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
3585 *(sp + 5) = (png_byte)(v & 0xff);
3586 }
3587 }
3588 }
3589
3590 else
3591 #endif
3592 {
3593 sp = row;
3594 for (i = 0; i < row_width; i++, sp += 6)
3595 {
3596 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3597
3598 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
3599 + *(sp + 3));
3600
3601 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
3602 + *(sp + 5));
3603
3604 if (r == png_ptr->trans_color.red &&
3605 g == png_ptr->trans_color.green &&
3606 b == png_ptr->trans_color.blue)
3607 {
3608 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3609 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3610 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3611 & 0xff);
3612 *(sp + 3) = (png_byte)(png_ptr->background.green
3613 & 0xff);
3614 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3615 & 0xff);
3616 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3617 }
3618 }
3619 }
3620 }
3621 break;
3622 }
3623
3624 case PNG_COLOR_TYPE_GRAY_ALPHA:
3625 {
3626 if (row_info->bit_depth == 8)
3627 {
3628 #ifdef PNG_READ_GAMMA_SUPPORTED
3629 if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
3630 gamma_table != NULL)
3631 {
3632 sp = row;
3633 for (i = 0; i < row_width; i++, sp += 2)
3634 {
3635 png_uint_16 a = *(sp + 1);
3636
3637 if (a == 0xff)
3638 *sp = gamma_table[*sp];
3639
3640 else if (a == 0)
3641 {
3642 /* Background is already in screen gamma */
3643 *sp = (png_byte)png_ptr->background.gray;
3644 }
3645
3646 else
3647 {
3648 png_byte v, w;
3649
3650 v = gamma_to_1[*sp];
3651 png_composite(w, v, a, png_ptr->background_1.gray);
3652 if (optimize == 0)
3653 w = gamma_from_1[w];
3654 *sp = w;
3655 }
3656 }
3657 }
3658 else
3659 #endif
3660 {
3661 sp = row;
3662 for (i = 0; i < row_width; i++, sp += 2)
3663 {
3664 png_byte a = *(sp + 1);
3665
3666 if (a == 0)
3667 *sp = (png_byte)png_ptr->background.gray;
3668
3669 else if (a < 0xff)
3670 png_composite(*sp, *sp, a, png_ptr->background.gray);
3671 }
3672 }
3673 }
3674 else /* if (png_ptr->bit_depth == 16) */
3675 {
3676 #ifdef PNG_READ_GAMMA_SUPPORTED
3677 if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
3678 gamma_16_to_1 != NULL)
3679 {
3680 sp = row;
3681 for (i = 0; i < row_width; i++, sp += 4)
3682 {
3683 png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8)
3684 + *(sp + 3));
3685
3686 if (a == (png_uint_16)0xffff)
3687 {
3688 png_uint_16 v;
3689
3690 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3691 *sp = (png_byte)((v >> 8) & 0xff);
3692 *(sp + 1) = (png_byte)(v & 0xff);
3693 }
3694
3695 else if (a == 0)
3696 {
3697 /* Background is already in screen gamma */
3698 *sp = (png_byte)((png_ptr->background.gray >> 8)
3699 & 0xff);
3700 *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
3701 }
3702
3703 else
3704 {
3705 png_uint_16 g, v, w;
3706
3707 g = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
3708 png_composite_16(v, g, a, png_ptr->background_1.gray);
3709 if (optimize != 0)
3710 w = v;
3711 else
3712 w = gamma_16_from_1[(v & 0xff) >>
3713 gamma_shift][v >> 8];
3714 *sp = (png_byte)((w >> 8) & 0xff);
3715 *(sp + 1) = (png_byte)(w & 0xff);
3716 }
3717 }
3718 }
3719 else
3720 #endif
3721 {
3722 sp = row;
3723 for (i = 0; i < row_width; i++, sp += 4)
3724 {
3725 png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8)
3726 + *(sp + 3));
3727
3728 if (a == 0)
3729 {
3730 *sp = (png_byte)((png_ptr->background.gray >> 8)
3731 & 0xff);
3732 *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
3733 }
3734
3735 else if (a < 0xffff)
3736 {
3737 png_uint_16 g, v;
3738
3739 g = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3740 png_composite_16(v, g, a, png_ptr->background.gray);
3741 *sp = (png_byte)((v >> 8) & 0xff);
3742 *(sp + 1) = (png_byte)(v & 0xff);
3743 }
3744 }
3745 }
3746 }
3747 break;
3748 }
3749
3750 case PNG_COLOR_TYPE_RGB_ALPHA:
3751 {
3752 if (row_info->bit_depth == 8)
3753 {
3754 #ifdef PNG_READ_GAMMA_SUPPORTED
3755 if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
3756 gamma_table != NULL)
3757 {
3758 sp = row;
3759 for (i = 0; i < row_width; i++, sp += 4)
3760 {
3761 png_byte a = *(sp + 3);
3762
3763 if (a == 0xff)
3764 {
3765 *sp = gamma_table[*sp];
3766 *(sp + 1) = gamma_table[*(sp + 1)];
3767 *(sp + 2) = gamma_table[*(sp + 2)];
3768 }
3769
3770 else if (a == 0)
3771 {
3772 /* Background is already in screen gamma */
3773 *sp = (png_byte)png_ptr->background.red;
3774 *(sp + 1) = (png_byte)png_ptr->background.green;
3775 *(sp + 2) = (png_byte)png_ptr->background.blue;
3776 }
3777
3778 else
3779 {
3780 png_byte v, w;
3781
3782 v = gamma_to_1[*sp];
3783 png_composite(w, v, a, png_ptr->background_1.red);
3784 if (optimize == 0) w = gamma_from_1[w];
3785 *sp = w;
3786
3787 v = gamma_to_1[*(sp + 1)];
3788 png_composite(w, v, a, png_ptr->background_1.green);
3789 if (optimize == 0) w = gamma_from_1[w];
3790 *(sp + 1) = w;
3791
3792 v = gamma_to_1[*(sp + 2)];
3793 png_composite(w, v, a, png_ptr->background_1.blue);
3794 if (optimize == 0) w = gamma_from_1[w];
3795 *(sp + 2) = w;
3796 }
3797 }
3798 }
3799 else
3800 #endif
3801 {
3802 sp = row;
3803 for (i = 0; i < row_width; i++, sp += 4)
3804 {
3805 png_byte a = *(sp + 3);
3806
3807 if (a == 0)
3808 {
3809 *sp = (png_byte)png_ptr->background.red;
3810 *(sp + 1) = (png_byte)png_ptr->background.green;
3811 *(sp + 2) = (png_byte)png_ptr->background.blue;
3812 }
3813
3814 else if (a < 0xff)
3815 {
3816 png_composite(*sp, *sp, a, png_ptr->background.red);
3817
3818 png_composite(*(sp + 1), *(sp + 1), a,
3819 png_ptr->background.green);
3820
3821 png_composite(*(sp + 2), *(sp + 2), a,
3822 png_ptr->background.blue);
3823 }
3824 }
3825 }
3826 }
3827 else /* if (row_info->bit_depth == 16) */
3828 {
3829 #ifdef PNG_READ_GAMMA_SUPPORTED
3830 if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
3831 gamma_16_to_1 != NULL)
3832 {
3833 sp = row;
3834 for (i = 0; i < row_width; i++, sp += 8)
3835 {
3836 png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6))
3837 << 8) + (png_uint_16)(*(sp + 7)));
3838
3839 if (a == (png_uint_16)0xffff)
3840 {
3841 png_uint_16 v;
3842
3843 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
3844 *sp = (png_byte)((v >> 8) & 0xff);
3845 *(sp + 1) = (png_byte)(v & 0xff);
3846
3847 v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)];
3848 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
3849 *(sp + 3) = (png_byte)(v & 0xff);
3850
3851 v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)];
3852 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
3853 *(sp + 5) = (png_byte)(v & 0xff);
3854 }
3855
3856 else if (a == 0)
3857 {
3858 /* Background is already in screen gamma */
3859 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3860 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3861 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3862 & 0xff);
3863 *(sp + 3) = (png_byte)(png_ptr->background.green
3864 & 0xff);
3865 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3866 & 0xff);
3867 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3868 }
3869
3870 else
3871 {
3872 png_uint_16 v, w;
3873
3874 v = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
3875 png_composite_16(w, v, a, png_ptr->background_1.red);
3876 if (optimize == 0)
3877 w = gamma_16_from_1[((w & 0xff) >> gamma_shift)][w >>
3878 8];
3879 *sp = (png_byte)((w >> 8) & 0xff);
3880 *(sp + 1) = (png_byte)(w & 0xff);
3881
3882 v = gamma_16_to_1[*(sp + 3) >> gamma_shift][*(sp + 2)];
3883 png_composite_16(w, v, a, png_ptr->background_1.green);
3884 if (optimize == 0)
3885 w = gamma_16_from_1[((w & 0xff) >> gamma_shift)][w >>
3886 8];
3887
3888 *(sp + 2) = (png_byte)((w >> 8) & 0xff);
3889 *(sp + 3) = (png_byte)(w & 0xff);
3890
3891 v = gamma_16_to_1[*(sp + 5) >> gamma_shift][*(sp + 4)];
3892 png_composite_16(w, v, a, png_ptr->background_1.blue);
3893 if (optimize == 0)
3894 w = gamma_16_from_1[((w & 0xff) >> gamma_shift)][w >>
3895 8];
3896
3897 *(sp + 4) = (png_byte)((w >> 8) & 0xff);
3898 *(sp + 5) = (png_byte)(w & 0xff);
3899 }
3900 }
3901 }
3902
3903 else
3904 #endif
3905 {
3906 sp = row;
3907 for (i = 0; i < row_width; i++, sp += 8)
3908 {
3909 png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6))
3910 << 8) + (png_uint_16)(*(sp + 7)));
3911
3912 if (a == 0)
3913 {
3914 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
3915 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
3916 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
3917 & 0xff);
3918 *(sp + 3) = (png_byte)(png_ptr->background.green
3919 & 0xff);
3920 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
3921 & 0xff);
3922 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
3923 }
3924
3925 else if (a < 0xffff)
3926 {
3927 png_uint_16 v;
3928
3929 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
3930 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
3931 + *(sp + 3));
3932 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
3933 + *(sp + 5));
3934
3935 png_composite_16(v, r, a, png_ptr->background.red);
3936 *sp = (png_byte)((v >> 8) & 0xff);
3937 *(sp + 1) = (png_byte)(v & 0xff);
3938
3939 png_composite_16(v, g, a, png_ptr->background.green);
3940 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
3941 *(sp + 3) = (png_byte)(v & 0xff);
3942
3943 png_composite_16(v, b, a, png_ptr->background.blue);
3944 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
3945 *(sp + 5) = (png_byte)(v & 0xff);
3946 }
3947 }
3948 }
3949 }
3950 break;
3951 }
3952
3953 default:
3954 break;
3955 }
3956 }
3957 #endif /* READ_BACKGROUND || READ_ALPHA_MODE */
3958
3959 #ifdef PNG_READ_GAMMA_SUPPORTED
3960 /* Gamma correct the image, avoiding the alpha channel. Make sure
3961 * you do this after you deal with the transparency issue on grayscale
3962 * or RGB images. If your bit depth is 8, use gamma_table, if it
3963 * is 16, use gamma_16_table and gamma_shift. Build these with
3964 * build_gamma_table().
3965 */
3966 static void
3967 png_do_gamma(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
3968 {
3969 png_const_bytep gamma_table = png_ptr->gamma_table;
3970 png_const_uint_16pp gamma_16_table = png_ptr->gamma_16_table;
3971 int gamma_shift = png_ptr->gamma_shift;
3972
3973 png_bytep sp;
3974 png_uint_32 i;
3975 png_uint_32 row_width=row_info->width;
3976
3977 png_debug(1, "in png_do_gamma");
3978
3979 if (((row_info->bit_depth <= 8 && gamma_table != NULL) ||
3980 (row_info->bit_depth == 16 && gamma_16_table != NULL)))
3981 {
3982 switch (row_info->color_type)
3983 {
3984 case PNG_COLOR_TYPE_RGB:
3985 {
3986 if (row_info->bit_depth == 8)
3987 {
3988 sp = row;
3989 for (i = 0; i < row_width; i++)
3990 {
3991 *sp = gamma_table[*sp];
3992 sp++;
3993 *sp = gamma_table[*sp];
3994 sp++;
3995 *sp = gamma_table[*sp];
3996 sp++;
3997 }
3998 }
3999
4000 else /* if (row_info->bit_depth == 16) */
4001 {
4002 sp = row;
4003 for (i = 0; i < row_width; i++)
4004 {
4005 png_uint_16 v;
4006
4007 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4008 *sp = (png_byte)((v >> 8) & 0xff);
4009 *(sp + 1) = (png_byte)(v & 0xff);
4010 sp += 2;
4011
4012 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4013 *sp = (png_byte)((v >> 8) & 0xff);
4014 *(sp + 1) = (png_byte)(v & 0xff);
4015 sp += 2;
4016
4017 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4018 *sp = (png_byte)((v >> 8) & 0xff);
4019 *(sp + 1) = (png_byte)(v & 0xff);
4020 sp += 2;
4021 }
4022 }
4023 break;
4024 }
4025
4026 case PNG_COLOR_TYPE_RGB_ALPHA:
4027 {
4028 if (row_info->bit_depth == 8)
4029 {
4030 sp = row;
4031 for (i = 0; i < row_width; i++)
4032 {
4033 *sp = gamma_table[*sp];
4034 sp++;
4035
4036 *sp = gamma_table[*sp];
4037 sp++;
4038
4039 *sp = gamma_table[*sp];
4040 sp++;
4041
4042 sp++;
4043 }
4044 }
4045
4046 else /* if (row_info->bit_depth == 16) */
4047 {
4048 sp = row;
4049 for (i = 0; i < row_width; i++)
4050 {
4051 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4052 *sp = (png_byte)((v >> 8) & 0xff);
4053 *(sp + 1) = (png_byte)(v & 0xff);
4054 sp += 2;
4055
4056 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4057 *sp = (png_byte)((v >> 8) & 0xff);
4058 *(sp + 1) = (png_byte)(v & 0xff);
4059 sp += 2;
4060
4061 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4062 *sp = (png_byte)((v >> 8) & 0xff);
4063 *(sp + 1) = (png_byte)(v & 0xff);
4064 sp += 4;
4065 }
4066 }
4067 break;
4068 }
4069
4070 case PNG_COLOR_TYPE_GRAY_ALPHA:
4071 {
4072 if (row_info->bit_depth == 8)
4073 {
4074 sp = row;
4075 for (i = 0; i < row_width; i++)
4076 {
4077 *sp = gamma_table[*sp];
4078 sp += 2;
4079 }
4080 }
4081
4082 else /* if (row_info->bit_depth == 16) */
4083 {
4084 sp = row;
4085 for (i = 0; i < row_width; i++)
4086 {
4087 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4088 *sp = (png_byte)((v >> 8) & 0xff);
4089 *(sp + 1) = (png_byte)(v & 0xff);
4090 sp += 4;
4091 }
4092 }
4093 break;
4094 }
4095
4096 case PNG_COLOR_TYPE_GRAY:
4097 {
4098 if (row_info->bit_depth == 2)
4099 {
4100 sp = row;
4101 for (i = 0; i < row_width; i += 4)
4102 {
4103 int a = *sp & 0xc0;
4104 int b = *sp & 0x30;
4105 int c = *sp & 0x0c;
4106 int d = *sp & 0x03;
4107
4108 *sp = (png_byte)(
4109 ((((int)gamma_table[a|(a>>2)|(a>>4)|(a>>6)]) ) & 0xc0)|
4110 ((((int)gamma_table[(b<<2)|b|(b>>2)|(b>>4)])>>2) & 0x30)|
4111 ((((int)gamma_table[(c<<4)|(c<<2)|c|(c>>2)])>>4) & 0x0c)|
4112 ((((int)gamma_table[(d<<6)|(d<<4)|(d<<2)|d])>>6) ));
4113 sp++;
4114 }
4115 }
4116
4117 if (row_info->bit_depth == 4)
4118 {
4119 sp = row;
4120 for (i = 0; i < row_width; i += 2)
4121 {
4122 int msb = *sp & 0xf0;
4123 int lsb = *sp & 0x0f;
4124
4125 *sp = (png_byte)((((int)gamma_table[msb | (msb >> 4)]) & 0xf0)
4126 | (((int)gamma_table[(lsb << 4) | lsb]) >> 4));
4127 sp++;
4128 }
4129 }
4130
4131 else if (row_info->bit_depth == 8)
4132 {
4133 sp = row;
4134 for (i = 0; i < row_width; i++)
4135 {
4136 *sp = gamma_table[*sp];
4137 sp++;
4138 }
4139 }
4140
4141 else if (row_info->bit_depth == 16)
4142 {
4143 sp = row;
4144 for (i = 0; i < row_width; i++)
4145 {
4146 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
4147 *sp = (png_byte)((v >> 8) & 0xff);
4148 *(sp + 1) = (png_byte)(v & 0xff);
4149 sp += 2;
4150 }
4151 }
4152 break;
4153 }
4154
4155 default:
4156 break;
4157 }
4158 }
4159 }
4160 #endif
4161
4162 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
4163 /* Encode the alpha channel to the output gamma (the input channel is always
4164 * linear.) Called only with color types that have an alpha channel. Needs the
4165 * from_1 tables.
4166 */
4167 static void
4168 png_do_encode_alpha(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
4169 {
4170 png_uint_32 row_width = row_info->width;
4171
4172 png_debug(1, "in png_do_encode_alpha");
4173
4174 if ((row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0)
4175 {
4176 if (row_info->bit_depth == 8)
4177 {
4178 png_bytep table = png_ptr->gamma_from_1;
4179
4180 if (table != NULL)
4181 {
4182 int step = (row_info->color_type & PNG_COLOR_MASK_COLOR) ? 4 : 2;
4183
4184 /* The alpha channel is the last component: */
4185 row += step - 1;
4186
4187 for (; row_width > 0; --row_width, row += step)
4188 *row = table[*row];
4189
4190 return;
4191 }
4192 }
4193
4194 else if (row_info->bit_depth == 16)
4195 {
4196 png_uint_16pp table = png_ptr->gamma_16_from_1;
4197 int gamma_shift = png_ptr->gamma_shift;
4198
4199 if (table != NULL)
4200 {
4201 int step = (row_info->color_type & PNG_COLOR_MASK_COLOR) ? 8 : 4;
4202
4203 /* The alpha channel is the last component: */
4204 row += step - 2;
4205
4206 for (; row_width > 0; --row_width, row += step)
4207 {
4208 png_uint_16 v;
4209
4210 v = table[*(row + 1) >> gamma_shift][*row];
4211 *row = (png_byte)((v >> 8) & 0xff);
4212 *(row + 1) = (png_byte)(v & 0xff);
4213 }
4214
4215 return;
4216 }
4217 }
4218 }
4219
4220 /* Only get to here if called with a weird row_info; no harm has been done,
4221 * so just issue a warning.
4222 */
4223 png_warning(png_ptr, "png_do_encode_alpha: unexpected call");
4224 }
4225 #endif
4226
4227 #ifdef PNG_READ_EXPAND_SUPPORTED
4228 /* Expands a palette row to an RGB or RGBA row depending
4229 * upon whether you supply trans and num_trans.
4230 */
4231 static void
4232 png_do_expand_palette(png_structrp png_ptr, png_row_infop row_info,
4233 png_bytep row, png_const_colorp palette, png_const_bytep trans_alpha,
4234 int num_trans)
4235 {
4236 int shift, value;
4237 png_bytep sp, dp;
4238 png_uint_32 i;
4239 png_uint_32 row_width=row_info->width;
4240
4241 png_debug(1, "in png_do_expand_palette");
4242
4243 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
4244 {
4245 if (row_info->bit_depth < 8)
4246 {
4247 switch (row_info->bit_depth)
4248 {
4249 case 1:
4250 {
4251 sp = row + (size_t)((row_width - 1) >> 3);
4252 dp = row + (size_t)row_width - 1;
4253 shift = 7 - (int)((row_width + 7) & 0x07);
4254 for (i = 0; i < row_width; i++)
4255 {
4256 if ((*sp >> shift) & 0x01)
4257 *dp = 1;
4258
4259 else
4260 *dp = 0;
4261
4262 if (shift == 7)
4263 {
4264 shift = 0;
4265 sp--;
4266 }
4267
4268 else
4269 shift++;
4270
4271 dp--;
4272 }
4273 break;
4274 }
4275
4276 case 2:
4277 {
4278 sp = row + (size_t)((row_width - 1) >> 2);
4279 dp = row + (size_t)row_width - 1;
4280 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
4281 for (i = 0; i < row_width; i++)
4282 {
4283 value = (*sp >> shift) & 0x03;
4284 *dp = (png_byte)value;
4285 if (shift == 6)
4286 {
4287 shift = 0;
4288 sp--;
4289 }
4290
4291 else
4292 shift += 2;
4293
4294 dp--;
4295 }
4296 break;
4297 }
4298
4299 case 4:
4300 {
4301 sp = row + (size_t)((row_width - 1) >> 1);
4302 dp = row + (size_t)row_width - 1;
4303 shift = (int)((row_width & 0x01) << 2);
4304 for (i = 0; i < row_width; i++)
4305 {
4306 value = (*sp >> shift) & 0x0f;
4307 *dp = (png_byte)value;
4308 if (shift == 4)
4309 {
4310 shift = 0;
4311 sp--;
4312 }
4313
4314 else
4315 shift += 4;
4316
4317 dp--;
4318 }
4319 break;
4320 }
4321
4322 default:
4323 break;
4324 }
4325 row_info->bit_depth = 8;
4326 row_info->pixel_depth = 8;
4327 row_info->rowbytes = row_width;
4328 }
4329
4330 if (row_info->bit_depth == 8)
4331 {
4332 {
4333 if (num_trans > 0)
4334 {
4335 sp = row + (size_t)row_width - 1;
4336 dp = row + ((size_t)row_width << 2) - 1;
4337
4338 i = 0;
4339 #ifdef PNG_ARM_NEON_INTRINSICS_AVAILABLE
4340 if (png_ptr->riffled_palette != NULL)
4341 {
4342 /* The RGBA optimization works with png_ptr->bit_depth == 8
4343 * but sometimes row_info->bit_depth has been changed to 8.
4344 * In these cases, the palette hasn't been riffled.
4345 */
4346 i = png_do_expand_palette_rgba8_neon(png_ptr, row_info, row,
4347 &sp, &dp);
4348 }
4349 #else
4350 PNG_UNUSED(png_ptr)
4351 #endif
4352
4353 for (; i < row_width; i++)
4354 {
4355 if ((int)(*sp) >= num_trans)
4356 *dp-- = 0xff;
4357 else
4358 *dp-- = trans_alpha[*sp];
4359 *dp-- = palette[*sp].blue;
4360 *dp-- = palette[*sp].green;
4361 *dp-- = palette[*sp].red;
4362 sp--;
4363 }
4364 row_info->bit_depth = 8;
4365 row_info->pixel_depth = 32;
4366 row_info->rowbytes = row_width * 4;
4367 row_info->color_type = 6;
4368 row_info->channels = 4;
4369 }
4370
4371 else
4372 {
4373 sp = row + (size_t)row_width - 1;
4374 dp = row + (size_t)(row_width * 3) - 1;
4375 i = 0;
4376 #ifdef PNG_ARM_NEON_INTRINSICS_AVAILABLE
4377 i = png_do_expand_palette_rgb8_neon(png_ptr, row_info, row,
4378 &sp, &dp);
4379 #else
4380 PNG_UNUSED(png_ptr)
4381 #endif
4382
4383 for (; i < row_width; i++)
4384 {
4385 *dp-- = palette[*sp].blue;
4386 *dp-- = palette[*sp].green;
4387 *dp-- = palette[*sp].red;
4388 sp--;
4389 }
4390
4391 row_info->bit_depth = 8;
4392 row_info->pixel_depth = 24;
4393 row_info->rowbytes = row_width * 3;
4394 row_info->color_type = 2;
4395 row_info->channels = 3;
4396 }
4397 }
4398 }
4399 }
4400 }
4401
4402 /* If the bit depth < 8, it is expanded to 8. Also, if the already
4403 * expanded transparency value is supplied, an alpha channel is built.
4404 */
4405 static void
4406 png_do_expand(png_row_infop row_info, png_bytep row,
4407 png_const_color_16p trans_color)
4408 {
4409 int shift, value;
4410 png_bytep sp, dp;
4411 png_uint_32 i;
4412 png_uint_32 row_width=row_info->width;
4413
4414 png_debug(1, "in png_do_expand");
4415
4416 if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
4417 {
4418 unsigned int gray = trans_color != NULL ? trans_color->gray : 0;
4419
4420 if (row_info->bit_depth < 8)
4421 {
4422 switch (row_info->bit_depth)
4423 {
4424 case 1:
4425 {
4426 gray = (gray & 0x01) * 0xff;
4427 sp = row + (size_t)((row_width - 1) >> 3);
4428 dp = row + (size_t)row_width - 1;
4429 shift = 7 - (int)((row_width + 7) & 0x07);
4430 for (i = 0; i < row_width; i++)
4431 {
4432 if ((*sp >> shift) & 0x01)
4433 *dp = 0xff;
4434
4435 else
4436 *dp = 0;
4437
4438 if (shift == 7)
4439 {
4440 shift = 0;
4441 sp--;
4442 }
4443
4444 else
4445 shift++;
4446
4447 dp--;
4448 }
4449 break;
4450 }
4451
4452 case 2:
4453 {
4454 gray = (gray & 0x03) * 0x55;
4455 sp = row + (size_t)((row_width - 1) >> 2);
4456 dp = row + (size_t)row_width - 1;
4457 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
4458 for (i = 0; i < row_width; i++)
4459 {
4460 value = (*sp >> shift) & 0x03;
4461 *dp = (png_byte)(value | (value << 2) | (value << 4) |
4462 (value << 6));
4463 if (shift == 6)
4464 {
4465 shift = 0;
4466 sp--;
4467 }
4468
4469 else
4470 shift += 2;
4471
4472 dp--;
4473 }
4474 break;
4475 }
4476
4477 case 4:
4478 {
4479 gray = (gray & 0x0f) * 0x11;
4480 sp = row + (size_t)((row_width - 1) >> 1);
4481 dp = row + (size_t)row_width - 1;
4482 shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
4483 for (i = 0; i < row_width; i++)
4484 {
4485 value = (*sp >> shift) & 0x0f;
4486 *dp = (png_byte)(value | (value << 4));
4487 if (shift == 4)
4488 {
4489 shift = 0;
4490 sp--;
4491 }
4492
4493 else
4494 shift = 4;
4495
4496 dp--;
4497 }
4498 break;
4499 }
4500
4501 default:
4502 break;
4503 }
4504
4505 row_info->bit_depth = 8;
4506 row_info->pixel_depth = 8;
4507 row_info->rowbytes = row_width;
4508 }
4509
4510 if (trans_color != NULL)
4511 {
4512 if (row_info->bit_depth == 8)
4513 {
4514 gray = gray & 0xff;
4515 sp = row + (size_t)row_width - 1;
4516 dp = row + ((size_t)row_width << 1) - 1;
4517
4518 for (i = 0; i < row_width; i++)
4519 {
4520 if ((*sp & 0xffU) == gray)
4521 *dp-- = 0;
4522
4523 else
4524 *dp-- = 0xff;
4525
4526 *dp-- = *sp--;
4527 }
4528 }
4529
4530 else if (row_info->bit_depth == 16)
4531 {
4532 unsigned int gray_high = (gray >> 8) & 0xff;
4533 unsigned int gray_low = gray & 0xff;
4534 sp = row + row_info->rowbytes - 1;
4535 dp = row + (row_info->rowbytes << 1) - 1;
4536 for (i = 0; i < row_width; i++)
4537 {
4538 if ((*(sp - 1) & 0xffU) == gray_high &&
4539 (*(sp) & 0xffU) == gray_low)
4540 {
4541 *dp-- = 0;
4542 *dp-- = 0;
4543 }
4544
4545 else
4546 {
4547 *dp-- = 0xff;
4548 *dp-- = 0xff;
4549 }
4550
4551 *dp-- = *sp--;
4552 *dp-- = *sp--;
4553 }
4554 }
4555
4556 row_info->color_type = PNG_COLOR_TYPE_GRAY_ALPHA;
4557 row_info->channels = 2;
4558 row_info->pixel_depth = (png_byte)(row_info->bit_depth << 1);
4559 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
4560 row_width);
4561 }
4562 }
4563 else if (row_info->color_type == PNG_COLOR_TYPE_RGB &&
4564 trans_color != NULL)
4565 {
4566 if (row_info->bit_depth == 8)
4567 {
4568 png_byte red = (png_byte)(trans_color->red & 0xff);
4569 png_byte green = (png_byte)(trans_color->green & 0xff);
4570 png_byte blue = (png_byte)(trans_color->blue & 0xff);
4571 sp = row + (size_t)row_info->rowbytes - 1;
4572 dp = row + ((size_t)row_width << 2) - 1;
4573 for (i = 0; i < row_width; i++)
4574 {
4575 if (*(sp - 2) == red && *(sp - 1) == green && *(sp) == blue)
4576 *dp-- = 0;
4577
4578 else
4579 *dp-- = 0xff;
4580
4581 *dp-- = *sp--;
4582 *dp-- = *sp--;
4583 *dp-- = *sp--;
4584 }
4585 }
4586 else if (row_info->bit_depth == 16)
4587 {
4588 png_byte red_high = (png_byte)((trans_color->red >> 8) & 0xff);
4589 png_byte green_high = (png_byte)((trans_color->green >> 8) & 0xff);
4590 png_byte blue_high = (png_byte)((trans_color->blue >> 8) & 0xff);
4591 png_byte red_low = (png_byte)(trans_color->red & 0xff);
4592 png_byte green_low = (png_byte)(trans_color->green & 0xff);
4593 png_byte blue_low = (png_byte)(trans_color->blue & 0xff);
4594 sp = row + row_info->rowbytes - 1;
4595 dp = row + ((size_t)row_width << 3) - 1;
4596 for (i = 0; i < row_width; i++)
4597 {
4598 if (*(sp - 5) == red_high &&
4599 *(sp - 4) == red_low &&
4600 *(sp - 3) == green_high &&
4601 *(sp - 2) == green_low &&
4602 *(sp - 1) == blue_high &&
4603 *(sp ) == blue_low)
4604 {
4605 *dp-- = 0;
4606 *dp-- = 0;
4607 }
4608
4609 else
4610 {
4611 *dp-- = 0xff;
4612 *dp-- = 0xff;
4613 }
4614
4615 *dp-- = *sp--;
4616 *dp-- = *sp--;
4617 *dp-- = *sp--;
4618 *dp-- = *sp--;
4619 *dp-- = *sp--;
4620 *dp-- = *sp--;
4621 }
4622 }
4623 row_info->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
4624 row_info->channels = 4;
4625 row_info->pixel_depth = (png_byte)(row_info->bit_depth << 2);
4626 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
4627 }
4628 }
4629 #endif
4630
4631 #ifdef PNG_READ_EXPAND_16_SUPPORTED
4632 /* If the bit depth is 8 and the color type is not a palette type expand the
4633 * whole row to 16 bits. Has no effect otherwise.
4634 */
4635 static void
4636 png_do_expand_16(png_row_infop row_info, png_bytep row)
4637 {
4638 if (row_info->bit_depth == 8 &&
4639 row_info->color_type != PNG_COLOR_TYPE_PALETTE)
4640 {
4641 /* The row have a sequence of bytes containing [0..255] and we need
4642 * to turn it into another row containing [0..65535], to do this we
4643 * calculate:
4644 *
4645 * (input / 255) * 65535
4646 *
4647 * Which happens to be exactly input * 257 and this can be achieved
4648 * simply by byte replication in place (copying backwards).
4649 */
4650 png_byte *sp = row + row_info->rowbytes; /* source, last byte + 1 */
4651 png_byte *dp = sp + row_info->rowbytes; /* destination, end + 1 */
4652 while (dp > sp)
4653 {
4654 dp[-2] = dp[-1] = *--sp; dp -= 2;
4655 }
4656
4657 row_info->rowbytes *= 2;
4658 row_info->bit_depth = 16;
4659 row_info->pixel_depth = (png_byte)(row_info->channels * 16);
4660 }
4661 }
4662 #endif
4663
4664 #ifdef PNG_READ_QUANTIZE_SUPPORTED
4665 static void
4666 png_do_quantize(png_row_infop row_info, png_bytep row,
4667 png_const_bytep palette_lookup, png_const_bytep quantize_lookup)
4668 {
4669 png_bytep sp, dp;
4670 png_uint_32 i;
4671 png_uint_32 row_width=row_info->width;
4672
4673 png_debug(1, "in png_do_quantize");
4674
4675 if (row_info->bit_depth == 8)
4676 {
4677 if (row_info->color_type == PNG_COLOR_TYPE_RGB && palette_lookup)
4678 {
4679 int r, g, b, p;
4680 sp = row;
4681 dp = row;
4682 for (i = 0; i < row_width; i++)
4683 {
4684 r = *sp++;
4685 g = *sp++;
4686 b = *sp++;
4687
4688 /* This looks real messy, but the compiler will reduce
4689 * it down to a reasonable formula. For example, with
4690 * 5 bits per color, we get:
4691 * p = (((r >> 3) & 0x1f) << 10) |
4692 * (((g >> 3) & 0x1f) << 5) |
4693 * ((b >> 3) & 0x1f);
4694 */
4695 p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) &
4696 ((1 << PNG_QUANTIZE_RED_BITS) - 1)) <<
4697 (PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) |
4698 (((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) &
4699 ((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) <<
4700 (PNG_QUANTIZE_BLUE_BITS)) |
4701 ((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) &
4702 ((1 << PNG_QUANTIZE_BLUE_BITS) - 1));
4703
4704 *dp++ = palette_lookup[p];
4705 }
4706
4707 row_info->color_type = PNG_COLOR_TYPE_PALETTE;
4708 row_info->channels = 1;
4709 row_info->pixel_depth = row_info->bit_depth;
4710 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
4711 }
4712
4713 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA &&
4714 palette_lookup != NULL)
4715 {
4716 int r, g, b, p;
4717 sp = row;
4718 dp = row;
4719 for (i = 0; i < row_width; i++)
4720 {
4721 r = *sp++;
4722 g = *sp++;
4723 b = *sp++;
4724 sp++;
4725
4726 p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) &
4727 ((1 << PNG_QUANTIZE_RED_BITS) - 1)) <<
4728 (PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) |
4729 (((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) &
4730 ((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) <<
4731 (PNG_QUANTIZE_BLUE_BITS)) |
4732 ((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) &
4733 ((1 << PNG_QUANTIZE_BLUE_BITS) - 1));
4734
4735 *dp++ = palette_lookup[p];
4736 }
4737
4738 row_info->color_type = PNG_COLOR_TYPE_PALETTE;
4739 row_info->channels = 1;
4740 row_info->pixel_depth = row_info->bit_depth;
4741 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
4742 }
4743
4744 else if (row_info->color_type == PNG_COLOR_TYPE_PALETTE &&
4745 quantize_lookup)
4746 {
4747 sp = row;
4748
4749 for (i = 0; i < row_width; i++, sp++)
4750 {
4751 *sp = quantize_lookup[*sp];
4752 }
4753 }
4754 }
4755 }
4756 #endif /* READ_QUANTIZE */
4757
4758 /* Transform the row. The order of transformations is significant,
4759 * and is very touchy. If you add a transformation, take care to
4760 * decide how it fits in with the other transformations here.
4761 */
4762 void /* PRIVATE */
4763 png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)
4764 {
4765 png_debug(1, "in png_do_read_transformations");
4766
4767 if (png_ptr->row_buf == NULL)
4768 {
4769 /* Prior to 1.5.4 this output row/pass where the NULL pointer is, but this
4770 * error is incredibly rare and incredibly easy to debug without this
4771 * information.
4772 */
4773 png_error(png_ptr, "NULL row buffer");
4774 }
4775
4776 /* The following is debugging; prior to 1.5.4 the code was never compiled in;
4777 * in 1.5.4 PNG_FLAG_DETECT_UNINITIALIZED was added and the macro
4778 * PNG_WARN_UNINITIALIZED_ROW removed. In 1.6 the new flag is set only for
4779 * all transformations, however in practice the ROW_INIT always gets done on
4780 * demand, if necessary.
4781 */
4782 if ((png_ptr->flags & PNG_FLAG_DETECT_UNINITIALIZED) != 0 &&
4783 (png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
4784 {
4785 /* Application has failed to call either png_read_start_image() or
4786 * png_read_update_info() after setting transforms that expand pixels.
4787 * This check added to libpng-1.2.19 (but not enabled until 1.5.4).
4788 */
4789 png_error(png_ptr, "Uninitialized row");
4790 }
4791
4792 #ifdef PNG_READ_EXPAND_SUPPORTED
4793 if ((png_ptr->transformations & PNG_EXPAND) != 0)
4794 {
4795 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
4796 {
4797 #ifdef PNG_ARM_NEON_INTRINSICS_AVAILABLE
4798 if ((png_ptr->num_trans > 0) && (png_ptr->bit_depth == 8))
4799 {
4800 if (png_ptr->riffled_palette == NULL)
4801 {
4802 /* Initialize the accelerated palette expansion. */
4803 png_ptr->riffled_palette =
4804 (png_bytep)png_malloc(png_ptr, 256 * 4);
4805 png_riffle_palette_neon(png_ptr);
4806 }
4807 }
4808 #endif
4809 png_do_expand_palette(png_ptr, row_info, png_ptr->row_buf + 1,
4810 png_ptr->palette, png_ptr->trans_alpha, png_ptr->num_trans);
4811 }
4812
4813 else
4814 {
4815 if (png_ptr->num_trans != 0 &&
4816 (png_ptr->transformations & PNG_EXPAND_tRNS) != 0)
4817 png_do_expand(row_info, png_ptr->row_buf + 1,
4818 &(png_ptr->trans_color));
4819
4820 else
4821 png_do_expand(row_info, png_ptr->row_buf + 1, NULL);
4822 }
4823 }
4824 #endif
4825
4826 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
4827 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
4828 (png_ptr->transformations & PNG_COMPOSE) == 0 &&
4829 (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
4830 row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
4831 png_do_strip_channel(row_info, png_ptr->row_buf + 1,
4832 0 /* at_start == false, because SWAP_ALPHA happens later */);
4833 #endif
4834
4835 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
4836 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
4837 {
4838 int rgb_error =
4839 png_do_rgb_to_gray(png_ptr, row_info,
4840 png_ptr->row_buf + 1);
4841
4842 if (rgb_error != 0)
4843 {
4844 png_ptr->rgb_to_gray_status=1;
4845 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
4846 PNG_RGB_TO_GRAY_WARN)
4847 png_warning(png_ptr, "png_do_rgb_to_gray found nongray pixel");
4848
4849 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
4850 PNG_RGB_TO_GRAY_ERR)
4851 png_error(png_ptr, "png_do_rgb_to_gray found nongray pixel");
4852 }
4853 }
4854 #endif
4855
4856 /* From Andreas Dilger e-mail to png-implement, 26 March 1998:
4857 *
4858 * In most cases, the "simple transparency" should be done prior to doing
4859 * gray-to-RGB, or you will have to test 3x as many bytes to check if a
4860 * pixel is transparent. You would also need to make sure that the
4861 * transparency information is upgraded to RGB.
4862 *
4863 * To summarize, the current flow is:
4864 * - Gray + simple transparency -> compare 1 or 2 gray bytes and composite
4865 * with background "in place" if transparent,
4866 * convert to RGB if necessary
4867 * - Gray + alpha -> composite with gray background and remove alpha bytes,
4868 * convert to RGB if necessary
4869 *
4870 * To support RGB backgrounds for gray images we need:
4871 * - Gray + simple transparency -> convert to RGB + simple transparency,
4872 * compare 3 or 6 bytes and composite with
4873 * background "in place" if transparent
4874 * (3x compare/pixel compared to doing
4875 * composite with gray bkgrnd)
4876 * - Gray + alpha -> convert to RGB + alpha, composite with background and
4877 * remove alpha bytes (3x float
4878 * operations/pixel compared with composite
4879 * on gray background)
4880 *
4881 * Greg's change will do this. The reason it wasn't done before is for
4882 * performance, as this increases the per-pixel operations. If we would check
4883 * in advance if the background was gray or RGB, and position the gray-to-RGB
4884 * transform appropriately, then it would save a lot of work/time.
4885 */
4886
4887 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
4888 /* If gray -> RGB, do so now only if background is non-gray; else do later
4889 * for performance reasons
4890 */
4891 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0 &&
4892 (png_ptr->mode & PNG_BACKGROUND_IS_GRAY) == 0)
4893 png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
4894 #endif
4895
4896 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
4897 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
4898 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
4899 png_do_compose(row_info, png_ptr->row_buf + 1, png_ptr);
4900 #endif
4901
4902 #ifdef PNG_READ_GAMMA_SUPPORTED
4903 if ((png_ptr->transformations & PNG_GAMMA) != 0 &&
4904 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
4905 /* Because RGB_TO_GRAY does the gamma transform. */
4906 (png_ptr->transformations & PNG_RGB_TO_GRAY) == 0 &&
4907 #endif
4908 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
4909 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
4910 /* Because PNG_COMPOSE does the gamma transform if there is something to
4911 * do (if there is an alpha channel or transparency.)
4912 */
4913 !((png_ptr->transformations & PNG_COMPOSE) != 0 &&
4914 ((png_ptr->num_trans != 0) ||
4915 (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)) &&
4916 #endif
4917 /* Because png_init_read_transformations transforms the palette, unless
4918 * RGB_TO_GRAY will do the transform.
4919 */
4920 (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE))
4921 png_do_gamma(row_info, png_ptr->row_buf + 1, png_ptr);
4922 #endif
4923
4924 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
4925 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
4926 (png_ptr->transformations & PNG_COMPOSE) != 0 &&
4927 (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
4928 row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
4929 png_do_strip_channel(row_info, png_ptr->row_buf + 1,
4930 0 /* at_start == false, because SWAP_ALPHA happens later */);
4931 #endif
4932
4933 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
4934 if ((png_ptr->transformations & PNG_ENCODE_ALPHA) != 0 &&
4935 (row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0)
4936 png_do_encode_alpha(row_info, png_ptr->row_buf + 1, png_ptr);
4937 #endif
4938
4939 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
4940 if ((png_ptr->transformations & PNG_SCALE_16_TO_8) != 0)
4941 png_do_scale_16_to_8(row_info, png_ptr->row_buf + 1);
4942 #endif
4943
4944 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
4945 /* There is no harm in doing both of these because only one has any effect,
4946 * by putting the 'scale' option first if the app asks for scale (either by
4947 * calling the API or in a TRANSFORM flag) this is what happens.
4948 */
4949 if ((png_ptr->transformations & PNG_16_TO_8) != 0)
4950 png_do_chop(row_info, png_ptr->row_buf + 1);
4951 #endif
4952
4953 #ifdef PNG_READ_QUANTIZE_SUPPORTED
4954 if ((png_ptr->transformations & PNG_QUANTIZE) != 0)
4955 {
4956 png_do_quantize(row_info, png_ptr->row_buf + 1,
4957 png_ptr->palette_lookup, png_ptr->quantize_index);
4958
4959 if (row_info->rowbytes == 0)
4960 png_error(png_ptr, "png_do_quantize returned rowbytes=0");
4961 }
4962 #endif /* READ_QUANTIZE */
4963
4964 #ifdef PNG_READ_EXPAND_16_SUPPORTED
4965 /* Do the expansion now, after all the arithmetic has been done. Notice
4966 * that previous transformations can handle the PNG_EXPAND_16 flag if this
4967 * is efficient (particularly true in the case of gamma correction, where
4968 * better accuracy results faster!)
4969 */
4970 if ((png_ptr->transformations & PNG_EXPAND_16) != 0)
4971 png_do_expand_16(row_info, png_ptr->row_buf + 1);
4972 #endif
4973
4974 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
4975 /* NOTE: moved here in 1.5.4 (from much later in this list.) */
4976 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0 &&
4977 (png_ptr->mode & PNG_BACKGROUND_IS_GRAY) != 0)
4978 png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
4979 #endif
4980
4981 #ifdef PNG_READ_INVERT_SUPPORTED
4982 if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
4983 png_do_invert(row_info, png_ptr->row_buf + 1);
4984 #endif
4985
4986 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
4987 if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0)
4988 png_do_read_invert_alpha(row_info, png_ptr->row_buf + 1);
4989 #endif
4990
4991 #ifdef PNG_READ_SHIFT_SUPPORTED
4992 if ((png_ptr->transformations & PNG_SHIFT) != 0)
4993 png_do_unshift(row_info, png_ptr->row_buf + 1,
4994 &(png_ptr->shift));
4995 #endif
4996
4997 #ifdef PNG_READ_PACK_SUPPORTED
4998 if ((png_ptr->transformations & PNG_PACK) != 0)
4999 png_do_unpack(row_info, png_ptr->row_buf + 1);
5000 #endif
5001
5002 #ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
5003 /* Added at libpng-1.5.10 */
5004 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE &&
5005 png_ptr->num_palette_max >= 0)
5006 png_do_check_palette_indexes(png_ptr, row_info);
5007 #endif
5008
5009 #ifdef PNG_READ_BGR_SUPPORTED
5010 if ((png_ptr->transformations & PNG_BGR) != 0)
5011 png_do_bgr(row_info, png_ptr->row_buf + 1);
5012 #endif
5013
5014 #ifdef PNG_READ_PACKSWAP_SUPPORTED
5015 if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
5016 png_do_packswap(row_info, png_ptr->row_buf + 1);
5017 #endif
5018
5019 #ifdef PNG_READ_FILLER_SUPPORTED
5020 if ((png_ptr->transformations & PNG_FILLER) != 0)
5021 png_do_read_filler(row_info, png_ptr->row_buf + 1,
5022 (png_uint_32)png_ptr->filler, png_ptr->flags);
5023 #endif
5024
5025 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
5026 if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0)
5027 png_do_read_swap_alpha(row_info, png_ptr->row_buf + 1);
5028 #endif
5029
5030 #ifdef PNG_READ_16BIT_SUPPORTED
5031 #ifdef PNG_READ_SWAP_SUPPORTED
5032 if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
5033 png_do_swap(row_info, png_ptr->row_buf + 1);
5034 #endif
5035 #endif
5036
5037 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
5038 if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
5039 {
5040 if (png_ptr->read_user_transform_fn != NULL)
5041 (*(png_ptr->read_user_transform_fn)) /* User read transform function */
5042 (png_ptr, /* png_ptr */
5043 row_info, /* row_info: */
5044 /* png_uint_32 width; width of row */
5045 /* size_t rowbytes; number of bytes in row */
5046 /* png_byte color_type; color type of pixels */
5047 /* png_byte bit_depth; bit depth of samples */
5048 /* png_byte channels; number of channels (1-4) */
5049 /* png_byte pixel_depth; bits per pixel (depth*channels) */
5050 png_ptr->row_buf + 1); /* start of pixel data for row */
5051 #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
5052 if (png_ptr->user_transform_depth != 0)
5053 row_info->bit_depth = png_ptr->user_transform_depth;
5054
5055 if (png_ptr->user_transform_channels != 0)
5056 row_info->channels = png_ptr->user_transform_channels;
5057 #endif
5058 row_info->pixel_depth = (png_byte)(row_info->bit_depth *
5059 row_info->channels);
5060
5061 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_info->width);
5062 }
5063 #endif
5064 }
5065
5066 #endif /* READ_TRANSFORMS */
5067 #endif /* READ */